The plaintiff has standing where it is the holder or assignee of the underlying note at the time the action is commenced. Either a written assignment of the underlying note or its physical delivery prior to the commencement of the action is sufficient to transfer the obligation, and the mortgage passes with the debt as an inseparable incident. Where, as here, the plaintiff's standing is placed in issue by the defendant's answer, the plaintiff must prove its standing.
Bank of N.Y. Mellon v. Deas, NY Slip Op 07536 (2d Dep't December 29, 2021)