Haw. Rev. Stat. § 560:1-108

For the purpose of granting consent or approval with regard to the acts or accounts of a personal representative or trustee, including relief from liability or penalty for failure to post bond, to register a trust, or to perform other duties, and for purposes of consenting to modification or termination of a trust or to deviation from its terms, the sole holder or all co-holders 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.