coop society Nomination

1)Original member of housing society died in 1990 gave nomination of X & Y in 1973 . 2) X & Y claimed membership in 1994 on the basis of Nomination. 3) In 2003 X gave nomination of a & b and Y gave nomination of c. 4) X & Y died n 2013. 5) One person claiming to be legal heir of ORiGinAL member objecting to the nomination of a,b & c saying that X & Y had no right to nominate a,b, & c as X & Y themselves became members through nomination. Though the so called legal heir have not obtained any succession certificate from competent court. WHat are the options to a, b & c as the so called legal heir moved an application u/ s 25a of mcs act read with sec 25 to deputy registrar for deletion of names of X & Y and objecting to the nomination of a,b & c.