Registered Release Deed

Mr Prakash expired intestate. Mr Prakash's wife died six months later. Leaving behind them two sons A and B. Mr Prakash married only once. Mr. Prakash left behind an immovable property. A flat in a co-operative housing society. In the records of the society Mr. Prakash had made the nomination in favor of his sons A and B. A and B entered into a release deed in which B transferred all his rights to A in the property. A then also put up an advertisement in regional and national daily. A and B also presented an notarized affidavit A also submitted the death certificates of Mr Prakash and his wife the property got transferred in the share certificate and records of the society. Now, A wants to sell the property. However, one bank while sanctioning the loan asked for succession certificate, while other bank cleared the loan So my question is whether , in the above specific case, a succession certificate is required or a registered release deed and an affidavit along with newspaper advertisement would do.... Kindly answer my question in detail.