Mont. Code Ann. § 42-4-202
Parties to department or agency placement
42-4-202 . Parties to department or agency placement. A parent of a child may relinquish the child for adoption to the department or a licensed child-placing agency. The department or agency shall agree in writing to accept the relinquishment of a placing parent as provided in 42-2-402 before the relinquishment is valid.