(1) A surrogate designated by a grantor in an advance directive for mental health treatment shall act on behalf of the grantor in accordance with the desires of the grantor as indicated in the advance directive and may override the advance directive only if there is substantial medical evidence that failing to do so would result in harm to the grantor.
(2) When acting on behalf of the grantor, the surrogate shall consider the recommendations of the health care provider and honor the decisions made by the grantor as expressed in the advance directive.
(3) If the grantor's instructions or preferences are not stated in the advance directive, the surrogate may act in good faith on behalf of the grantor in the manner that the surrogate believes the grantor would act.
(4) A surrogate may resign at any time by giving written notice to the grantor, to the immediate successor surrogate, if any, to the attending health care provider, or to the health care facility.