N.Y. Debtor & Creditor Law § 70

§ 70. Opposing creditor to file proofs, if not named in schedule.\nWhere the name of an opposing creditor does not appear in the schedule,\nhe must file, with the specification of his objections, proof, by\naffidavit, that he is a creditor; and, if his debt is not set forth in\nthe schedule, he must also file his affidavit, to the effect specified\nin subdivisions first and second of section sixty-one of this chapter.\n