N.Y. UCT Law § 1814

§ 1814. Designation of defendant; amendment procedure.\n (a) A party who is ignorant, in whole or in part, of the true name of\na person, partnership, firm or corporation which may properly be made a\nparty defendant, may proceed against such defendant in any name used by\nthe person, partnership, firm or corporation in conducting business, as\ndefined in subdivision (a) of section eighteen hundred thirteen of this\narticle.\n (b) If the true name of the defendant becomes known at any time prior\nto the hearing on the merits, such information shall be brought to the\nattention of the clerk, who shall immediately amend all prior\nproceedings and papers. The clerk shall send an amended notice to the\ndefendant, without payment of additional fees by the plaintiff, and all\nsubsequent proceedings and papers shall be amended accordingly.\n (c) In every action in the small claims part, at the hearing on the\nmerits, the judge or arbitrator shall determine the defendant's true\nname. The clerk shall amend all prior proceedings and papers to conform\nto such determination, and all subsequent proceedings and papers shall\nbe amended accordingly.\n (d) A party against whom a judgment has been entered pursuant to this\narticle, in any proceeding under section five thousand fifteen of the\ncivil practice law and rules for relief from such judgment, shall,\ndisclose its true name; any and all names in which it is conducting\nbusiness; and any and all names in which it was conducting business at\nthe time of the transaction or occurrence on which such judgment is\nbased. All subsequent proceedings and papers shall be amended to conform\nto such disclosure.\n