Rule 21. Improper Joinder and Nonjoinder of Parties;  Severance

Joinder of a party that is not permitted under Rule 20(a) is not a ground to dismiss an entire action. At any time--on terms that are just--the court may dismiss an improperly joined party or join any party who may be properly joined under Rule 20(a). The court may also sever any claim against a party, and that severed claim may proceed as a separate and independent action.