La. Code Civ. Proc. art. 1091 : Code of Civil Procedure — ORDINARY PROCEEDINGS — PLEADING — INCIDENTAL ACTIONS — INTERVENTION — Third person may intervene
A third person having an interest therein may intervene in a pending action to enforce a right related to or connected with the object of the pending action against one or more of the parties thereto by:
(1) Joining with plaintiff in demanding the same or similar relief against the defendant;
(2) Uniting with defendant in resisting the plaintiff's demand; or
(3) Opposing both plaintiff and defendant.