Any sale or encumbrance to a conservator, the spouse, agent, attorney of a conservator or any corporation, trust, or other organization in which the conservator has a substantial beneficial interest, or any other transaction involving the estate being administered by the conservator which is affected by a substantial conflict between fiduciary and personal interests is voidable unless the transaction is approved by the court after notice as directed by the court.
Mass. Gen. Laws ch. 190B, § 5-421