1977 co operative society

Hello sir My mom had purchased a flat in 1977 in Mumbai in Goregaon. In 2010 my mother made 100 percent nomination on my name in presence of the society members. In 2011 after my mother passed away, i got an affidavit done and also took an NOC affidavit from my elder sister which says that she has left all her rights from this property. Basis which the society transferred the flat ony name and also the share certificate. Now when I am selling my flat to one of the members from.the society itself, the current society is denying me NOC stating that i don't have succession certificate and also that this flat of 1977 should have been paid stamp.duty and registration. My question is that once the flat is transferred to me can the society ask for succession And now will i have to pay stamp duty registration for this.1977 flat, and if yes then how much would i have to bear. This.property is an ownership property and it.is approx.550 carpet. Please revert to me as it's very important to know