PROB §660: (a) The powerholder of a power of appointment that is presently exercisable, whether general or special, can contract to make an appointment to the same extent that the powerholder could make an effec

(a) The powerholder of a power of appointment that is presently exercisable, whether general or special, can contract to make an appointment to the same extent that the powerholder could make an effective appointment. (b) The powerholder of a power of appointment cannot contract to make an appointment while the power of appointment is not presently exercisable. If a promise to make an appointment under such a power is not performed, the promisee cannot obtain either specific performance or damages, but the promisee is not prevented from obtaining restitution of the value given by the promisee for the promise. (c) Unless the creating instrument expressly provides that the powerholder may not contract to make an appointment while the power of appointment is not presently exercisable, subdivision (b) does not apply to the case where the donor and the powerholder are the same person. In this case, the powerholder can contract to make an appointment to the same extent that the powerholder could make an effective appointment if the power of appointment were presently exercisable.