Ancestor property

Hi, i have a query, one of our property is in y grandmother name fr which my father wanted it to get transfered in his name but due to sudden death my mother took over and used to visit the court but when the time for inventory to be transfered in my mothers name, my mother too expired and we were unaware about the court issue , now we got to know that there was an inventory date given where my mother had to be present but guess the lawyer did not inform anyone or he did not have our contact number now in this case i want to know few things 1) what do i do in this case, should i register it again for inventory. 2) would i need to go begging again for my cousins signatures which my father had already taken. 3) if not required then how do i go ahead now registering it in all my siblings name. 4) Do you think without transfering it in our siblings name can we build our own house, and if yes then what all i need to think of or what are the measures to be taken care of. 5) one of my sibing is an NRI does that sibing too has equal rights Thank you Hinduja