Mont. Code § 85-7-1845
From any such judgment or decree an appeal may be taken to the supreme court by any party thereto at any time within 10 days of the entry of said judgment or decree. Such appeal shall be taken, perfected, and heard in the manner prescribed by Title 25 governing appeals from the district court to the supreme court. If no such appeal be taken within the time aforesaid or, if taken, the judgment or decree of the district court shall be affirmed by the supreme court, such judgment or decree shall be forever conclusive upon the parties thereto. In case contract has been made between the district and the United States, as provided in 85-7-1906, no change shall be made in the boundaries of the district, and the district court shall make no order changing the boundaries of the district until the secretary of the interior shall assent thereto in writing and such assent be filed with the district court.
§ 85-7-1845, MCA