(a) Grounds.(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 cross-claim or counterclaim.(b) Relation to Other Rules. This rule supplements and does not limit the joinder of parties allowed by Rule 20.