Misjoinder of parties is not a ground for dismissing an action. On motion or on its own, the court may at any time, on just terms, add or drop a party. The court may also sever any claim against a party.
Fed. R. Civ. P. 21
NOTES OF ADVISORY COMMITTEE ON RULES-1937 See English Rules Under the Judicature Act (The Annual Practice, 1937) O. 16, r. 11. See also [former] Equity Rules 43 (Defect of Parties-Resisting Objection) and 44 (Defect of Parties-Tardy Objection).For separate trials see Rules 13(i) (Counterclaims and Cross-Claims: Separate Trials; Separate Judgments), 20(b) (Permissive Joinder of Parties: Separate Trials), and 42(b) (Separate Trials, generally) and the note to the latter rule.
COMMITTEE NOTES ON RULES-2007 AMENDMENT The language of Rule 21 has been amended as part of the general restyling of the Civil Rules to make them more easily understood and to make style and terminology consistent throughout the rules. These changes are intended to be stylistic only.