N.Y. Real Property Actions & Proceedings Law § 1511: Additional parties

§ 1511. Additional parties. 1. In an action brought under this

article, the person in possession shall be made a party to the action,

and when such person claims the right of possession, or an interest in

the real property, under another, such other person shall also be made a

party.

2. Where it appears to the court that a person not a party to the

action may have an estate or interest in the real property which may in

any manner be affected by the judgment, the court, upon application of

such person, or of any party to the action, or on its own motion, may

direct that such person be made a party.