Transfer of share certificate/society membership

Me and my father jointly purchased the flat in Mumbai in year 2001, but in 2002 my father passed away without making a WILL. My elder sister was already married in 1989 and I had taken home loan to purchase my flat, my father had suffered a stroke even before we purchased the said flat and hence there was no way he could secure any funding for the purchase of the flat. But my name was not included in the purchase agreement of the said flat. When my father passed away in 2002, he had not made any WILL, and that made me, my elder sister and my mother as the legal heirs of our flat. Me and my elder sister gave the consent affidavit and NOC for transferring 100% shares on the name of my mother. And society made my mother as a Member in our society and issued a share certificate on her name. In 2018, my mother transferred her 1/3rd share in my name through relinquishment deed. So that made me as a 2/3rd owner of my flat. My mother then gave the application to our society to transfer share certificate on my name, but society refused by stating that mother is not a member she is a comember and hence she can not transfer the shared on my name based on relinquishment deed. I would like to know what does law say in this matter? Can our society refuse to transfer the 100% share certificate on my name and refuse to make me as a member of the society even though my mother has released all her rights in the said property in my name? What is a way out?