709.03 Power of appointment; property held in trust.—If property subject to a power of appointment is held in trust by a person, firm or corporation other than the donee or donees of the power, a written release, in whole or in part, of a power to appoint the same shall be delivered to such trustee or trustees before the written release becomes legally effective. In no other instance shall a delivery of a release, in whole or in part, of a power of appointment be necessary to the validity of such release.
