(settlor of revocable trust adjudicated as incompetent and brother appointed as limited guardian; settlor then amended trust which changed disposition of estate even though trust specified that settlor could not amend or revoke trust once determined to be incompetent; but, trust also said right to amend or revoke could be restored by court order or if trustee received written opinions from two “licensed physicians” that settlor was competent; two letters obtained, but only one physician “licensed”; settlor died and amendment challenged; trial court determined that amendment invalid and that decision affirmed on appeal).