Where the name of an opposing creditor does not appear in the schedule, he must file, with the specification of his objections, proof, by affidavit, that he is a creditor; and, if his debt is not set forth in the schedule, he must also file his affidavit, to the effect specified in subdivisions first and second of section sixty-one of this chapter.
N.Y. Debt. and Cred. Law § 70