N.Y. C.P.L.R. 1024

§ 1024. Unknown parties. A party who is ignorant, in whole or in part,\nof the name or identity of a person who may properly be made a party,\nmay proceed against such person as an unknown party by designating so\nmuch of his name and identity as is known. If the name or remainder of\nthe name becomes known all subsequent proceedings shall be taken under\nthe true name and all prior proceedings shall be deemed amended\naccordingly.\n