Mont. Code Ann. § 72-1-109

For the purpose of granting consent or approval with regard to the acts or accounts of a personal representative, including relief from liability or penalty for failure to post bond, or to perform other duties, the sole holder or all coholders of a presently exercisable general power of appointment, including one in the form of a power of amendment or revocation, are deemed to act for beneficiaries to the extent their interests (as objects, takers in default, or otherwise) are subject to the power.