Mont. Code Ann. § 71-1-231

71-1-231 . Redemption by multiple mortgagors. If there is more than one mortgagor or more than one person claiming under a mortgagor, some of whom are not entitled to maintain an action under the provisions of 71-1-230 or Title 27, chapter 2, any one of them who is entitled to maintain an action may redeem in the action a divided or undivided part of the mortgaged premises as the person's interest appears, and have an accounting for a part of the rents and profits proportionate to the person's interest in the mortgaged premises on payment of a part of the mortgage money bearing the same proportion to the whole of the money as the value of person's divided or undivided interest in the premises bears to the whole of the premises.