N.Y. Civil Practice Law & Rules § 1003: Nonjoinder and misjoinder of parties

§ 1003. Nonjoinder and misjoinder of parties. Nonjoinder of a party

who should be joined under section 1001 is a ground for dismissal of an

action without prejudice unless the court allows the action to proceed

without that party under the provisions of that section. Misjoinder of

parties is not a ground for dismissal of an action. Parties may be added

at any stage of the action by leave of court or by stipulation of all

parties who have appeared, or once without leave of court within twenty

days after service of the original summons or at anytime before the

period for responding to that summons expires or within twenty days

after service of a pleading responding to it. Parties may be dropped by

the court, on motion of any party or on its own initiative, at any stage

of the action and upon such terms as may be just. The court may order

any claim against a party severed and proceeded with separately.