PS
*-kVmV/-kVnV - your; you (genitive and accusative pronominal suffix, 2 pl.)
(Kogan 2009:69)
Just as the singular forms, the plural of the pronominal suffix of the 2nd person is based on the element k- with the extension -m- or -n- combined with more or less expressed vocalic oppositions (Kogan 2009:69). The character of consonantal and vocalic oppositions in individual languages generally corresponds to the nominative forms.