(a) Joinder, cross-claim, or counterclaim.
(1) By a Plaintiff. Persons with claims that may expose a plaintiff to double or multiple liability may be joined as defendants and required to interplead. Joinder for interpleader is proper even though:
(A) the claims of the several claimants, or the titles on which their claims depend, lack a common origin or are adverse and independent rather than identical; or
(B) the plaintiff denies liability in whole or in part to any or all of the claimants.
(2) By a Defendant. A defendant exposed to similar liability may seek interpleader through a crossclaim or counterclaim.
(1) Grounds. A defendant in a contract or property action may substitute as the defendant a person who is not a party and who demands the same debt or property at issue in the action, upon motion made:
(A) before the defendant files an answer;
(B) with due notice to the person not a party and to the plaintiff; and
(C) upon affidavit that a person not a party to the action:
(i) makes against the defendant a demand for the same debt or property, and
(ii) is not colluding with the defendant.
(2) Deposit of Debt or Delivery of Property. A defendant substituted under this rule must, at the court’s discretion, either:
(A) deposit in court the amount of the debt at issue; or
(B) deliver the property at issue or its value to such person as the court may direct.
(3) Discharge of Liability. A defendant’s deposit of debt or delivery of property under subsection (b)(2) discharges the defendant’s liability to either the plaintiff or the substitute defendant.
Interpleader solves a specific problem: you hold money or property that two or more people claim, and you risk having to pay it twice. Rule 22 lets you bring the rival claimants into one action and require them to interplead — to fight out their competing claims among themselves — so you are not caught between them. A plaintiff joins the claimants as defendants; a defendant seeks interpleader through a crossclaim or counterclaim.
Subdivision (b) adds a Montana substitution procedure: a defendant in a contract or property action may, before answering and on affidavit that a non-party demands the same debt or property and is not colluding, move to substitute that outsider as the defendant. The substituted defendant then deposits the debt or delivers the property as the court directs, which discharges the original defendant's liability.