The tenants whose units were specifically addressed in respondent's order, which reduced or vacated an administrative law judge's findings in their favor with regard to rent over-charges, were necessary parties whose rights may be directly and inequitably affected by the judgment (CPLR 1001 [a]). As respondent concedes, the tenants were indisputably subject to jurisdiction, and should be joined even if the limitations period has expired ( see Windy Ridge Farm v Assessor of Town of Shandaken, 11 NY3d 725), without prejudice to interposing such a defense ( see Friedland v Hickox, 60 AD3d 426). It is unnecessary at this point to consider the "relation back" doctrine.