Joint ownership trf 50%share

My flat is under redevelopment. Original agreement has joint ownership between me as first owner and my father who is deceased now. I have added my wife's name in society membership as member after deceased of my father as per the nomination. Now I have to execute PAAA with builder for my redevelopment falt. Me, my mother and elder sister are 3 legal heirs currently. Now I have been advised to execute release deed from mother and my sister to trf father's 50% share in my name so I can become 100% owner. What is the stamp duty and registration fees I will have to pay? How can I add my wife's name into the new agreement PAAA ? Since wife is joint member of the society do I have to execute any gift deed for 50% of ownership? In that case what will be the stamp duty and registration fees? I am also ok to execute new PAAA in my sole name without adding wife's name. Does it require wife to resign from society membership? I am not in position to pay high stamp duty. Flat value is aprox 80- 90 lakhs.