N.Y. RPA Law § 903

§ 903. Necessary defendants. Each of the following persons shall be\nmade a party to the action:\n 1. Every person having an undivided share, in possession or otherwise,\nin the property, as tenant in fee, for life, by the curtesy or for\nyears;\n 2. Every person entitled to the reversion, remainder or inheritance of\nan undivided share, after the determination of a particular estate\ntherein;\n 3. Every person who, by any contingency, is or may become entitled to\na beneficial interest in an undivided share in the property, provided\nthat where a future estate or interest is limited in any contingency to\nthe persons who shall compose a certain class upon the happening of a\nfuture event, it shall be sufficient to make parties to the action the\npersons who would have been entitled to such estate or interest if such\nevent had happened immediately before the commencement of the action;\n 4. Every person having an inchoate right of dower in an undivided\nshare in the property;\n 5. Every person having a right of dower in the property, or any part\nthereof, which has not been admeasured; and\n 6. An executor or administrator, where letters testamentary or of\nadministration have been issued on the estate of the decedent from whom\nthe plaintiff's title to the real property is derived, and the action is\nbrought within eighteen months after such letters were issued; or where\nthe person of whose estate the executor or administrator has been\nappointed should, if living, be a party to the action. If no executor or\nadministrator has been appointed for the estate of such a person, that\nfact must be stated in the complaint.\n