Michigan Compiled Laws, Chapter 556. Powers of Appointment § 556.120

Sec. 10.  (1) Unless the creating instrument provides otherwise, the donee of a power, presently exercisable, can contract to make an appointment, if neither the contract nor the promised appointment confers a benefit upon a person who is not a permissible appointee under the power.

(2) Unless the creating instrument provides otherwise, the donee of a power not presently exercisable cannot contract to make an appointment.  If the donee cannot contract to make an appointment, but nevertheless does so contract, the promisee cannot obtain either specific performance or damages, except that he can obtain damages equal to the value given by him for the promise.