Mont. Code Ann. § 70-29-201

The right of the several parties, plaintiff as well as defendant, may be put in issue, tried, and determined in the partition action. The title or interest of the plaintiff in the property, as stated in the complaint, may be controverted by the answer. The title or interest of any defendant in the property, as stated in the complaint, may also be controverted by the defendant's answer or the answer of any other defendant, and the title or interest of any defendant, as stated in that defendant's answer, may be controverted by the answer of any other defendant and the issues joined as prescribed in Title 25, which may be tried before a jury if the court directs.