Legal owner of house after mutation

Hi, I have some questions related to our ancestor property located at Kolkata suburb. This property was gifted to our family by then West Bengal government according to Refugee Rehabilitation (RR) act in 1950 and our ancestor built a house for living. After 40 years, by 1990, this land was registered as deed on 4 family members in our family – my father, uncle (father younger brother) and two of my aunts (father younger sisters). Couple of years ago, both of my parents and uncle died due to old age sickness; though my two aunts are alive, and the house is left empty. No one is living in that house. Now, we, as a family, have decided to sell this house but while talking to different concerned body like Municipality, registration office we came to know we have to do mutation for this house before selling to someone else as the last registered deed does not have some of our family member’s name who are now the legal heir of my parents and uncle. As per our understanding, me and my elder brother are legal heir of our parents and my auntie (uncle’s wife) and cousin brother (uncle’s son) are legal heir of my uncle. I have couple of questions: 1. Once we are done with mutation for this house will my cousin brother have rights to this house? Will his name be included as one of the owners in the mutation document? 2. Is he eligible for monitory claim as part of uncle’s right if the house gets sold to another party? Or only my auntie (uncle’s wife) can have claim? 3. Finally, how many members will be considered as claimant? Please response to these questions so that we can plan accordingly as we want what is supposed to be done; we are not going to deprive anyone or hurt anyone. We want to walk to that path which is correct and legal. Regards, Kusal