Mont. Code Ann. § 25-10-108

In an action prosecuted or defended by an executor, administrator, trustee of an express trust, or person expressly authorized by statute, costs may be recovered as in an action by and against a person prosecuting or defending in the person's own right. However, the costs must, by the judgment, be made chargeable only upon the estate, fund, or party represented unless the court directs the costs to be paid by the plaintiff or defendant personally for mismanagement or bad faith in the action or defense.