Ordered that the judgment is reversed, on the law, and a new trial is granted, with costs to abide the event.
In view of the discovery demands served by the defendants and the pretrial discovery order in this case, the trial court erred in allowing a witness who had never been disclosed to testify for the plaintiffs ( see, CPLR 3101 [a]). Under the circumstances of this case, a new trial is warranted ( see generally, Skowronski v F J Meat Packers, 210 A.D.2d 392). Contrary to the plaintiffs' position, the defendants did not open the door to the witness's testimony by virtue of the defendant Eugene F. Kuchner's testimony given on the plaintiffs' direct case. However, there is no reason to preclude the witness's testimony at the new trial as the defendants can no longer claim either surprise or lack of opportunity to prepare a responsive defense ( see, Skowronski v. F J Meat Packers, supra).
For the purposes of retrial, we note that the manner in which the preverdict interest computations were made by the trial court was inconsistent with Milbrandt v. Green Refractories Co. ( 79 N.Y.2d 26) and irreconcilable with the jury's verdict.
The defendants' remaining contention is without merit.
Bracken, J.P., Copertino, Sullivan and McGinity, JJ., concur.