New York Consolidated Laws, Estates, Powers and Trusts Law - EPT § 10-6.4 Exercise of a power of appointment;  required consents

(a) When the consent of the donor or of a third person to the exercise of a power of appointment is required, such consent shall be expressed in a written instrument, subscribed by the person whose consent is required;  and to entitle the instrument of exercise to be recorded, the signatures of the donee and of the person consenting must be acknowledged or proved in the manner required by the laws of this state for the recording of a deed of real property.

(b) Unless the donor expressly provides otherwise: