Although they had ample opportunity to do so, plaintiffs failed to demonstrate good cause for their delay in disclosing the expert witness information belatedly furnished only in their supplemental response ( see, Corning v. Carlin, 178 A.D.2d 576; CPLR 3101 [d] [1] [i]). Nor, for that matter, did plaintiffs demonstrate that their failure to disclose the subject information until three weeks before trial was not intentional, the inference of an intentional withholding arising naturally from the circumstance that one of the experts, although retained by plaintiffs as early as 1991, was not designated as an expert by plaintiffs until three weeks in advance of the scheduled August 18, 1997 trial date.
Since plaintiffs' "supplemental" bill was in fact an amended bill and was served subsequent to the note of issue and without leave of the court, it was a nullity ( Leon v. First Natl. City Bank, 224 A.D.2d 497). Further, although leave to amend pleadings is ordinarily freely given, an application for leave to amend would have been properly denied herein since plaintiffs' proposed amendment would have prejudiced defendants by materially altering plaintiffs' theory of recovery on the eve of trial. Indeed, "[w]hen an amendment to a pleading or a bill of particulars is sought at or on the eve of trial, judicial discretion in allowing such amendment should be "`discreet, circumspect, prudent and cautious"'" ( Volpe v. Good Samaritan Hosp., 213 A.D.2d 398, quoting Perricone v. City of New York, 96 A.D.2d 531, 533, affd 62 N.Y.2d 661), and where, as here, there is an "extended delay in moving to amend, an affidavit of reasonable excuse for the delay in making the motion and an affidavit of merit should be submitted in support of the motion" ( Volpe v. Good Samaritan Hosp., supra, at 398-399). Plaintiffs, however, offered no valid excuse for their failure to first seek amendment until three weeks before trial.
We have considered plaintiffs' remaining claims and find them unpersuasive.
Concur — Ellerin, J. P., Williams, Wallach and Tom, JJ.