Rights of "provisional member" admitted u/s 154-b-1 (18) clause c of msc act - redevelopment society

My mother by way of nomination was made the nominee member after my father died inestate. We are 4 siblings and she has gifted the house to her son's son without our consent. Now I want to claim my share. Please advise 

Please post the above query in a fresh thread.

The action of the Society to transfer the interest of your late father in the capital and property of the Society to your mother as nominee was legally valid. But she could not further alienate her rights to another person, whoever it is, and the Society cannot accept or register such alienation. The legal heirs of your late father can contest the alienation and claim their rights.