Given our preference for disposition of cases on the merits ( see, Santora McKay v. Mazzella, 211 A.D.2d 460, 463; DFI Communications v. Golden Penn Theatre Ticket Serv., 87 A.D.2d 778, 779), we find that the motion court improvidently exercised its discretion in denying plaintiffs' motion to vacate their default where they had demonstrated a meritorious cause of action and a reasonable excuse for their default ( see, Santora McKay v. Mazzella, supra, at 463; Glass v. Janbach Props., 73 A.D.2d 106, 110). The record clearly shows that their affidavit of merit, erroneously found to have raised a new theory of liability for which there had been no discovery, did no more than properly state, with greater specificity, a theory of medical malpractice that had been generally claimed in the bill of particulars. No new facts were alleged; thus defendant would not have been misled or prejudiced. Counsel's showing of actual engagement in another court constituted reasonable excuse for the default ( see, Zatorski v. Klein, 11 A.D.2d 790; Slaughter Co. v. Saul, 53 N.Y.S.2d 73 [App Term 1945]).
Concur — Ellerin, P. J., Williams, Mazzarelli and Buckley, JJ.