Selling a jointly owned flat which has been gift deeded

My Dad and Mom are joint holders of a property and we are 8 siblings. 1992: My Dad expired 1994: the society issued a Share certificate in the name of my mother. 2015: my mom gifted me the flat by way of a gift deed. We ended up paying stamp duty to the tune of 1.45 lakhs and registration - 30000. We had done this consulting a high court lawyer. We put up the flat for sale and also had a potential buyer who paid the token amount. He wanted the NOC from the society. We submitted the gift deed,affidavit and the share certificate(in 2018 - yes, we should have done this earlier but had no guidance). The Society on checking with their lawyer, denied my request stating that first, the gift deed was invalid since there was no mention of the legal heirs in the gift deed. Also, the share certificate didn't have the entry of transfer of ownership from joint(dad + mom) to mom. Now I'm trying to rectify this in a legal way so that neither my family nor the buyer faces issues. However, the advice I have been getting from the various high advocates I have been speaking to is getting me worried and confused. So far the advice I have been getting as to next steps are - Cancel the gift deed(needs to be done by mom and me inthe presence of a registrar) - Prepare a deed of release where all the siblings release their ownership to mom(needs the siblings to be physically present in front of registrar) - Once Mom has possession she can sell the flat - If the Gift Deed is not cancelled, I cant sell the flat for a year since we just submitted the gift deed Now, I am not interested in the gift deed and more that willing to cancel it. However one of the advocates said, I cannot cancel it. Sad enough, the gift deed that has been created is invalid, expensive and now the inability to cancel is frustrating Another lawyer also said the if we notarize a NOC(or affidavit - cant recollect the doc) from the siblings transferring release to mom and if that is submitted to the society, the deed of release was not necessary. I am not sure what the right process is now. Would appreciate guidance on this front to make the sale of the flat easier.