Okla. Stat. tit. 60 § 299.7
When the consent of the donor, or of any other person, is required by the donor for the exercise of a power of appointment, this consent shall be in writing. To entitle the instrument exercising the power to be recorded, the signature of any person consenting shall be acknowledged. If the consent is given in a separate instrument, that instrument shall be attached to the instrument exercising the power. If any person whose consent is required dies or becomes legally incapable of consenting, the donee may exercise the power with the consent of the other person whose consent is required. If there is no such person, the donee may exercise the power in the manner provided by Section 3 of this act, unless the donor has manifested a contrary intent in the instrument creating the power.
Okla. Stat. tit. 60, § 299.7