Closing the Tag-Along Venue Loophole: Limits on Interlocutory Appeals Under Texas Civil Practice & Remedies Code § 15.003(b)

I. Introduction

The Supreme Court of Texas’s decision in Rush Truck Centers of Texas, L.P. and Blue Bird Body Company v. Sayre, No. 24‑0040 (Tex. June 6, 2025), is a significant procedural ruling about when Texas courts of appeals have jurisdiction over interlocutory venue appeals in multi-plaintiff cases.

The underlying case is a products-liability and wrongful-death suit arising from a tragic school bus accident that killed six-year-old Emory Sayre in Parker County. Her parents, Sean and Tori Sayre, sued the bus manufacturer (Blue Bird Body Company) and the dealer (Rush Truck Centers of Texas, L.P.) in Dallas County. The defendants challenged venue and, after the trial court denied their motion to transfer, pursued an interlocutory appeal under Texas Civil Practice and Remedies Code § 15.003(b).

Instead of reaching the merits of the venue dispute (Dallas vs. Parker or Comal County), the Supreme Court focused on appellate jurisdiction. It held that the court of appeals lacked jurisdiction to entertain the interlocutory appeal because the mere existence of multiple plaintiffs does not trigger the right to an interlocutory venue appeal under § 15.003(b). The statute authorizes such appeals only when the trial court has actually made a determination whether a plaintiff independently established proper venue under § 15.003(a).

This opinion “closes the loophole” that many courts of appeals had created by allowing interlocutory appeals in virtually all multi-plaintiff venue disputes. It restores the primacy of the general rule in § 15.064(a): no interlocutory appeals from venue determinations, except in the narrow circumstances expressly provided by § 15.003(b).

II. Factual and Procedural Background

A. The underlying tragedy and claims

In April 2022, six-year-old Emory Sayre was killed by her school bus as she exited and crossed in front of it on her way home. The accident occurred in Parker County, Texas.

Key actors and facts:

Accident location: Parker County.
Manufacturer: Blue Bird Body Company (Georgia manufacturer of the school bus).
Dealer: Rush Truck Centers of Texas, L.P. (principal office in Comal County, but doing business as “Rush Bus Centers of Dallas” from a Dallas County facility at the time of the sale).
Purchaser: Brock Independent School District.

In September 2022, Emory’s parents, Sean and Tori, sued in Dallas County, asserting:

Against Blue Bird: strict liability; design defect; manufacturing defect; failure to warn; negligence; and gross negligence.
Against Rush Truck: strict liability; failure to warn; negligence; and gross negligence.

They initially sued Brock ISD as well but later dismissed those claims.

B. Plaintiffs’ venue theory: Dallas County

The parents relied on Texas’s “substantial part of the events” venue provision:

TEX. CIV. PRAC. & REM. CODE § 15.002(a)(1): “Except as otherwise provided by this subchapter or Subchapter B or C, all lawsuits shall be brought … in the county in which all or a substantial part of the events or omissions giving rise to the claim occurred.”

They contended that a substantial part of the relevant events occurred in Dallas County because Rush Truck allegedly:

Proposed, negotiated, and entered into the bus sale from its Dallas location;
Billed for the bus from Dallas County;
Registered the bus in Dallas County;
Inspected the bus in Dallas County; and
Passed title to Brock ISD in Dallas County.

If venue was proper in Dallas County as to Rush Truck under § 15.002(a)(1), plaintiffs could then keep Blue Bird in Dallas under the “anchor-defendant” rule:

TEX. CIV. PRAC. & REM. CODE § 15.005: In a suit with multiple defendants, if venue is proper as to one, it is proper as to all “in all claims or actions arising out of the same transaction, occurrence, or series of transactions or occurrences.”

C. Defendants’ venue challenge and interlocutory appeal

Rush Truck and Blue Bird moved to transfer venue to either:

Parker County: the accident site and where the Rush employee who negotiated the sale worked from home; or
Comal County: where Rush Truck’s principal office is located.

They characterized the Dallas County activities as “clerical and administrative,” arguing the real gravamen of the dispute lay elsewhere.

The trial court denied the motion to transfer. Defendants took an interlocutory appeal. The Dallas Court of Appeals held that a substantial part of the “supply” of the bus occurred in Dallas County and affirmed the trial court’s refusal to transfer venue. See Rush Truck Ctrs. of Tex., L.P. v. Sayre, 704 S.W.3d 857, 864–65 (Tex. App.—Dallas 2023).

Rush Truck and Blue Bird then petitioned for review to the Texas Supreme Court, challenging the court of appeals’ understanding of the venue statutes. After briefing on the venue merits, the Supreme Court sua sponte requested supplemental briefing on a threshold issue: whether the court of appeals had jurisdiction to entertain the interlocutory appeal at all, invoking its power to police jurisdiction:

“[T]his Court always has jurisdiction to determine its own, and the lower courts’, jurisdiction.”
Abbott v. Mexican Am. Legis. Caucus, Tex. House of Representatives, 647 S.W.3d 681, 699 (Tex. 2022).

III. Summary of the Opinion

A. The dispositive ruling

The Supreme Court did not decide whether Dallas County is a proper venue. Instead, it held that the Dallas Court of Appeals lacked jurisdiction to hear the interlocutory appeal because:

Texas generally forbids interlocutory appeals from venue determinations. TEX. CIV. PRAC. & REM. CODE § 15.064(a).
Section 15.003(b) creates only a narrow exception allowing an interlocutory appeal of a trial court’s “determination under Subsection (a)” — that is, a determination whether a plaintiff did or did not independently establish proper venue, or satisfied the joinder factors when they did not.
In this case, the Sayres asserted identical claims, based on identical facts, relying on identical venue grounds. The trial court therefore had no need to (and did not) decide whether each plaintiff “independently” established venue. It simply decided the venue question for the case as a whole.

Because there was no determination under § 15.003(a) regarding independent venue for each plaintiff, § 15.003(b) did not apply. And without that exception, § 15.064(a)’s general bar controlled, so no interlocutory appeal lay.

B. Disposition

The Court vacated the judgment of the Dallas Court of Appeals.
It remanded the case to the district court for further proceedings.
It expressly declined to reach the merits of the venue dispute, consistent with the principle that courts may not reach the merits when jurisdiction is lacking:
“The fundamental rule is that the Court may not reach the merits if it finds a single valid basis to defeat jurisdiction.”
Rattray v. City of Brownsville, 662 S.W.3d 860, 868 (Tex. 2023).

C. The new controlling principle

The key holding can be distilled as follows:

Rule: In multi-plaintiff suits, § 15.003(b) authorizes an interlocutory appeal of a venue ruling only when the trial court has made a determination under § 15.003(a) about whether a plaintiff (a) independently established proper venue, or (b) satisfied the four joinder criteria when they did not independently establish venue.
Corollary: The presence of multiple plaintiffs, by itself, is insufficient. When all plaintiffs rely on the same venue facts and same venue theory, and the trial court resolves venue globally rather than plaintiff-by-plaintiff, § 15.003(b) is not triggered. Section 15.064(a)’s general bar on interlocutory venue appeals therefore applies.

IV. Detailed Analysis

A. Statutory framework: §§ 15.064(a) and 15.003

1. General rule: no interlocutory appeals of venue rulings

Section 15.064(a) establishes the baseline:

“The court shall determine venue questions from the pleadings and affidavits. No interlocutory appeal shall lie from the determination.”
TEX. CIV. PRAC. & REM. CODE § 15.064(a) (emphasis added).

Enacted in 1983, this provision reflects the longstanding policy against piecemeal appeals: venue disputes are ordinarily reviewed, if at all, only after final judgment.

2. Exception in multi-plaintiff suits: § 15.003(a)–(b)

Section 15.003, governing multi-plaintiff suits, has two critical components.

a. The “independent venue” requirement – § 15.003(a)

Subsection (a) requires each plaintiff to “independently” establish proper venue, failing which their claims must be transferred or dismissed unless they meet four stringent joinder criteria:

“(a) In a suit in which there is more than one plaintiff … each plaintiff must, independently of every other plaintiff, establish proper venue. If a plaintiff cannot independently establish proper venue, that plaintiff’s part of the suit … must be transferred to a county of proper venue or dismissed, as is appropriate, unless that plaintiff … establishes that:

joinder … is proper …;

maintaining venue … does not unfairly prejudice another party …;

there is an essential need to have that plaintiff’s claim tried in the county …; and

the county … is a fair and convenient venue for that plaintiff and all persons against whom the suit is brought.”

TEX. CIV. PRAC. & REM. CODE § 15.003(a).

This provision was designed to prevent “tag-along” plaintiffs from piggybacking on a single plaintiff who could establish venue in a particular county (for example, a mass tort where only one plaintiff lives in the chosen county).

b. The interlocutory-appeal provision – § 15.003(b)

Subsection (b) is the jurisdictional gateway at issue:

“(b) An interlocutory appeal may be taken of a trial court’s determination under Subsection (a) that:

a plaintiff did or did not independently establish proper venue; or

a plaintiff that did not independently establish proper venue did or did not establish the items prescribed by Subsections (a)(1)-(4).”

TEX. CIV. PRAC. & REM. CODE § 15.003(b) (emphasis added).

The critical textual hook is the phrase “determination under Subsection (a)”. The Supreme Court’s opinion turns on a careful reading of that phrase in the broader statutory context.

B. Competing interpretations in the courts of appeals

1. The majority view: all multi-plaintiff venue rulings are appealable

Eleven courts of appeals had adopted a broad interpretation: in any multi-plaintiff suit, any venue determination is subject to interlocutory appeal under § 15.003(b). Cases illustrating this approach include:

Shamoun & Norman, LLP v. Yarto Int’l Grp., 398 S.W.3d 272, 285–87 (Tex. App.—Corpus Christi–Edinburg 2012, pet. dism’d).
Ryan Marine Servs., Inc. v. Hoffman, 668 S.W.3d 171, 179 (Tex. App.—Houston [1st Dist.] 2023, no pet.).
Jackson v. Jackson, No. 02‑15‑00102‑CV, 2016 WL 5220069, at *3 (Tex. App.—Fort Worth Sept. 22, 2016, pet. denied).
Clear Diamond, Inc. v. Zapata, No. 03‑20‑00057‑CV, 2021 WL 3572725, at *5 (Tex. App.—Austin Aug. 13, 2021, no pet.).
Flare Air, L.L.C. v. Burton, No. 06‑18‑00097‑CV, 2019 WL 166834, at *2 (Tex. App.—Texarkana Jan. 11, 2019, no pet.).
Nguyen v. Nguyen, No. 07‑24‑00093‑CV, 2024 WL 5049984, at *3 (Tex. App.—Amarillo Dec. 9, 2024, no pet.).
Brown v. Health & Med. Prac. Assocs., Inc., No. 09‑13‑00192‑CV, 2013 WL 5658605, at *2 (Tex. App.—Beaumont Oct. 17, 2013, no pet.).
In re AAA Bros. Holdings, LLC, No. 12‑23‑00210‑CV, 2023 WL 6631952, at *4 (Tex. App.—Tyler Oct. 11, 2023, orig. proceeding [mand. denied]).

Under this approach, § 15.003(b) was effectively treated as an override of § 15.064(a) in all multi-plaintiff cases, based on the specific-governs-the-general canon. The presence of multiple plaintiffs was enough.

2. The minority (Fourth Court) view: appealable only for plaintiffs who cannot independently establish venue

The Fourth Court of Appeals (San Antonio) took a narrower view in:

Basic Energy Servs. GP, LLC v. Gomez, 398 S.W.3d 734, 736 (Tex. App.—San Antonio 2010, no pet.).
Harding Bars, LLC v. McCaskill, 374 S.W.3d 517, 519–20 (Tex. App.—San Antonio 2012, pet. denied).

These cases held that § 15.003(b) interlocutory appeals are available “only to plaintiffs who are unable to independently establish venue apart from the joinder factors set out in § 15.003(a)”. If each plaintiff independently established venue (or the venue issue did not require plaintiff-specific analysis), § 15.003(b) did not apply, and § 15.064(a)’s blanket bar on interlocutory venue appeals remained in force.

In Rush Truck v. Sayre, the Supreme Court explicitly embraces the Fourth Court’s more restrictive interpretation and rejects the majority approach as inconsistent with the statutory text and structure.

C. The Supreme Court’s legal reasoning

1. Jurisdiction first

Echoing Steel Co. v. Citizens for a Better Env’t, 523 U.S. 83, 93–102 (1998), the Court emphasizes that jurisdictional questions take precedence:

Courts of appeals generally only have jurisdiction over final judgments. See Lehmann v. Har–Con Corp., 39 S.W.3d 191, 195 (Tex. 2001).
Interlocutory appeals are “narrow exceptions,” and statutes authorizing them must be strictly construed. See Tex. A&M Univ. Sys. v. Koseoglu, 233 S.W.3d 835, 841 (Tex. 2007).

Accordingly, the Court begins (and ends) with whether § 15.003(b) actually conferred appellate jurisdiction.

2. Reconciling §§ 15.064(a) and 15.003(b): the role of context

The Court resists reading § 15.003(b) so broadly that it would effectively nullify § 15.064(a). Instead, it applies the canon that statutes should be read as a whole, giving effect to each part where possible:

“Context is a primary determinant of meaning.” (citing SCALIA & GARNER, Reading Law at 167).
“The general/specific canon … deals with what to do when conflicting provisions simply cannot be reconciled …” (id. at 183). Here, reconciliation is possible.

Reading the provisions together, the Court concludes:

Section 15.064(a) sets the default rule: no interlocutory appeal from venue determinations.
Section 15.003(b) creates a limited carve-out for decisions the trial court makes under § 15.003(a) — specifically, determinations about whether individual plaintiffs independently established venue or met the joinder criteria.
Thus, § 15.003(b) applies only to plaintiff-specific venue determinations as contemplated by § 15.003(a), not to all venue decisions in multi-plaintiff cases.

3. Legislative history and the 2003 amendment

The opinion situates § 15.003 in its historical context, particularly the Court’s prior decision in American Home Products Corp. v. Clark, 38 S.W.3d 92 (Tex. 2000).

a. American Home Products (2000)

In American Home:

The Court construed an earlier version of § 15.003.
It held that the then-existing interlocutory-appeal provision applied only to orders granting or denying joinder or intervention, not to general venue determinations under § 15.002.
Allowing interlocutory appeals from any venue decision in a multi-plaintiff case would have contradicted § 15.064(a)’s bar on such appeals.

Thus, even then, the Court read the multi-plaintiff statute narrowly to preserve the general rule against interlocutory venue appeals.

b. The 2003 amendment to § 15.003

After American Home, the Legislature amended § 15.003 in 2003. The amendment:

Broadened the scope of appealable orders to include trial court “determination[s] … that a plaintiff did or did not independently establish proper venue.”
But the key phrase “determination under Subsection (a)” remained, preserving the link to § 15.003(a)’s structure and purpose.

The Supreme Court emphasizes that § 15.003, even after amendment, is “not a venue statute” in the general sense. It does not supplant the main venue rules in §§ 15.002, 15.005, and the like; rather, it adds an extra layer for multi-plaintiff cases to prevent misuse of “tag-along” venue.

Importantly, the Legislature did not:

Repeal § 15.064(a)’s categorical prohibition on interlocutory venue appeals;
Or state that any venue determination in a multiplaintiff case is immediately appealable.

The Court therefore refuses to infer such a sweeping change from the 2003 amendment, especially given the strong presumption against interlocutory appeals.

4. The “tag-along” problem and why it matters

The Court reads § 15.003 as targeting “tag-along” plaintiffs — those who:

Have no independent connection to the chosen venue; and
Attempt to hitch their claims to a plaintiff who does.

That concern is “apparent from the text” and was central in American Home, which involved eleven plaintiffs, only one of whom resided in the county of suit.

In such cases, § 15.003(a) forces each plaintiff to prove either:

Independent venue in the county; or
Satisfaction of the four joinder/judicial economy factors.

And § 15.003(b) then allows an interlocutory appeal of the trial court’s plaintiff-specific determination. This ensures that defendants can immediately challenge improper tag-along venue and prevent being forced to defend claims with no legitimate venue tie to the county.

In Rush Truck v. Sayre, by contrast:

Both plaintiffs (the parents) asserted the same wrongful-death and survival claims for their daughter’s death.
The venue facts they relied upon were identical.
The venue analysis would have been exactly the same even if there had been only one plaintiff (for example, a single parent).

Because there was no meaningful distinction between the plaintiffs, there was nothing for the trial court to decide “independently” as to each. The tag-along problem was simply absent. This, the Court concludes, is outside the intended and textual scope of § 15.003(b).

5. Adopting the Fourth Court’s interpretation

The Supreme Court expressly approves the Fourth Court’s holdings in Basic Energy and Harding Bars:

“The Fourth Court of Appeals has correctly recognized the limited scope of Section 15.003, holding that interlocutory appeals are available ‘only to plaintiffs who are unable to independently establish venue apart from the joinder factors set out in section 15.003(a).’”

Accordingly:

Interlocutory appeals are proper where the trial court has had to decide whether a particular plaintiff independently established venue or satisfied the (a)(1)–(4) factors — typically, where plaintiffs’ venue ties differ.
Interlocutory appeals are not proper where all plaintiffs present the same venue facts and claims, and the trial court’s order does not turn on plaintiff-specific differences.

6. The jurisdictional conclusion

The Court crystallizes its holding:

“We hold that where a trial court never needed to determine whether each plaintiff independently established proper venue — because the venue facts are identical for all the plaintiffs — Section 15.003(b)’s narrow exception does not apply, and Section 15.064(a)’s general rule against interlocutory venue appeals controls.”

Because that condition was met here, the Dallas Court of Appeals lacked jurisdiction. The Supreme Court therefore vacates its judgment under Texas Rule of Appellate Procedure 60.2(d) and remands to the district court.

V. Simplifying Key Concepts

A. What is “venue” and why does it matter?

“Venue” is the proper county in which a lawsuit may be filed and tried. It is distinct from:

Jurisdiction (the court’s power to hear the type of case), and
Choice of law (which state’s or country’s law applies).

Venue rules attempt to ensure that lawsuits are filed in a county that has a meaningful connection to the parties or the events giving rise to the dispute.

B. What is an “interlocutory appeal”?

An interlocutory appeal is an appeal from a trial court order made before final judgment. Because piecemeal appeals can delay and complicate litigation, Texas law allows them only where a statute expressly authorizes them, and those statutes are strictly construed.

Venue rulings are ordinarily challenged, if at all, only after final judgment, unless a statute like § 15.003(b) permits an earlier appeal.

C. “Independently establish proper venue”

This concept is central to § 15.003(a). To “independently” establish venue, a plaintiff must be able to show that, even if they were the only plaintiff in the lawsuit, the chosen county would still be a proper venue under the ordinary venue rules (e.g., because they reside there, the accident occurred there, or a substantial part of the events occurred there).

If a plaintiff cannot do that, they may still remain in the suit only by proving all four joinder criteria in § 15.003(a)(1)–(4), including no unfair prejudice to others and an “essential need” to try the claims in that county.

D. “Tag-along plaintiffs”

A “tag-along” plaintiff is one who has no legitimate venue connection to the chosen county but tries to join a lawsuit there solely because another plaintiff can establish venue. Section 15.003 was designed to prevent this kind of abuse in multi-plaintiff litigation, especially mass-tort and multi-county disputes.

E. The general/specific canon and statutory context

The general/specific canon is a rule of statutory construction: if a general provision conflicts with a more specific one, the specific provision is usually given priority. But that canon applies only when the provisions truly conflict and cannot be reconciled.

In this case, the Court reasons that §§ 15.064(a) (general ban on interlocutory venue appeals) and 15.003(b) (limited exception) can be reconciled: § 15.003(b) is read as a narrow exception for plaintiff-specific determinations under § 15.003(a), leaving § 15.064(a) in place for everything else.

VI. Impact and Practical Consequences

A. Immediate impact on the Rush Truck litigation

For the parties in this case:

The case is back in the district court in Dallas County.
The trial court’s denial of the motion to transfer venue stands for now, unreviewed on the merits.
Defendants cannot obtain immediate appellate review of the venue decision; they must proceed to litigate the case in Dallas County unless and until they can raise the venue issue on appeal after final judgment.

B. Clarified appellate jurisdiction in multi-plaintiff cases

The decision reshapes appellate practice statewide:

Court of appeals jurisdiction over venue rulings in multi-plaintiff cases is now clearly limited to:
- Orders deciding whether a specific plaintiff independently established venue; and
- Orders deciding whether a non-independent plaintiff met § 15.003(a)(1)–(4).
Interlocutory venue appeals are not available merely because:
- There are multiple plaintiffs; or
- The trial court denied or granted a motion to transfer venue in a multi-plaintiff case without making plaintiff-specific findings.

Practitioners should expect more aggressive jurisdictional screening by courts of appeals in venue-related interlocutory appeals and should be prepared to show, with record support, that the trial court made a qualifying “determination under Subsection (a).”

C. Effects on litigation strategy

1. For plaintiffs

Where multiple plaintiffs share the same venue facts, they are less likely to face protracted interlocutory appeals over venue, reducing delay and expense.
In mass or multi-county cases with disparate plaintiffs, plaintiffs must be prepared to satisfy § 15.003(a)’s independent venue or joinder requirements, knowing that trial court decisions thereon can be appealed immediately.
Plaintiffs who wish to avoid interlocutory appeals may, where appropriate, structure pleadings and proof so that all plaintiffs share the same venue basis; however, such strategy must be grounded in good faith factual reality and cannot be artificial.

2. For defendants

Defendants retain a potent tool against tag-along plaintiffs: motions under § 15.003(a) that force each plaintiff to prove independent venue or meet the joinder criteria, creating a record that can be the subject of an interlocutory appeal.
However, in “homogenous” multi-plaintiff cases like Sayre, defendants cannot rely on § 15.003(b) to obtain early review of ordinary venue disputes; they face the same constraints as in single-plaintiff litigation.
When seeking an interlocutory appeal, defendants should:
- Explicitly frame their motion and arguments under § 15.003(a);
- Request plaintiff-specific findings as to each plaintiff’s independent venue showing and joinder-factor compliance; and
- Ensure the trial court’s order or accompanying record reflects a clear “determination under Subsection (a).”

D. Clarifying and displacing prior appellate-court precedent

Although the Supreme Court does not formally list each disapproved case, its reasoning unmistakably rejects the holdings of most courts of appeals that had treated § 15.003(b) as authorizing interlocutory appeals in every multi-plaintiff venue dispute.

Going forward:

Opinions like Yarto and others cited in footnote (e.g., Ryan Marine, Clear Diamond, Flare Air, etc.) are effectively overruled to the extent they:
- Hold that the presence of multiple plaintiffs alone suffices to invoke § 15.003(b); or
- Treat § 15.003(b) as broadly overriding § 15.064(a) in multi-plaintiff cases.
The Fourth Court’s line of authority (Basic Energy, Harding Bars) is now endorsed and controlling.

E. Potential legislative responses

If the Legislature disagrees with this narrowing construction, it has options:

Amend § 15.003(b) to clearly state that any venue determination in a multi-plaintiff suit is immediately appealable; or
Amend or repeal § 15.064(a) to carve out a broader category of venue rulings subject to interlocutory appeal.

But under current text, as interpreted in Rush Truck v. Sayre, interlocutory venue appeals remain the exception, not the rule.

VII. Conclusion: Key Takeaways and Broader Significance

A. Core holdings in plain terms

Texas law strongly disfavors interlocutory appeals of venue decisions; § 15.064(a) codifies that general rule.
Section 15.003(b) is a narrow exception that applies only to trial court determinations made under § 15.003(a) regarding whether each plaintiff:
- Independently established proper venue, or
- Satisfied the joinder criteria when they did not.
The mere fact that a case involves multiple plaintiffs does not itself authorize an interlocutory appeal from a venue ruling.
When multiple plaintiffs share identical claims, facts, and venue grounds, and the trial court decides venue globally rather than plaintiff-by-plaintiff, § 15.003(b) is not triggered.
In such “homogenous” cases, any challenge to venue must ordinarily await final judgment.

B. Significance in the broader procedural landscape

Rush Truck v. Sayre is less about products liability or wrongful death than about civil procedure and appellate jurisdiction. Its importance lies in:

Reining in decades of expansive lower-court interpretations that had opened a “gaping jurisdictional loophole” for interlocutory venue appeals in multi-plaintiff suits;
Restoring the primacy of § 15.064(a)’s general bar and insisting that exceptions like § 15.003(b) be applied strictly and contextually;
Clarifying that § 15.003 is directed at the specific problem of tag-along plaintiffs, not a broad reworking of venue law;
Providing clearer guidance to courts and litigants on when an interlocutory venue appeal is—and is not—available.

By “closing the loophole” and carefully harmonizing §§ 15.003 and 15.064, the Supreme Court reinforces the final-judgment rule, discourages piecemeal appeals, and ensures that interlocutory review of venue determinations is reserved for the exceptional scenario that the Legislature actually targeted: the policing of improper tag-along plaintiffs in multi-plaintiff litigation.