456.1090.  Power to contract — presently exercisable power of appointment — power of appointment not presently exercisable. — 1.  A powerholder of a presently exercisable power of appointment may contract:

  (1)  Not to exercise the power; or

  (2)  To exercise the power if the contract when made does not confer a benefit on an impermissible appointee.

  2.  A powerholder of a power of appointment that is not presently exercisable may contract to exercise or not to exercise the power only if the powerholder:

  (1)  Is also the donor of the power; and

  (2)  Has reserved the power in a revocable trust.