Mont. Code Ann. § 50-16-804
Representative of deceased patient's estate
50-16-804 . Representative of deceased patient's estate. Except as provided in 50-19-402 , a personal representative of a deceased patient's estate may exercise all of the deceased patient's rights under this part. If there is no personal representative or upon discharge of the personal representative, a deceased patient's rights under this part may be exercised by the surviving spouse, a parent, an adult child, an adult sibling, or any other person who is authorized by law to act for the deceased person.