Firstly you should be aware that the NOC or affidavit or indemnity letter given by all legal heirs in favor of your grandmother intimating their relinquishment is not valid in the eyes of law. The creation of subsequent documents namely transferring all other revenue and taxation records on her name based on the unregistered affidavits or indemnity letter is also not valid.
As a matter of fact, the property devolved equally on all the legal heirs of your grandfather upon his intestate death in which your grandmother was also entitled to her share as one of the legal heirs.
Now upon your grandmother's death her share will also devolve on all ;ega; heirs equally.
Thus as per the prevailing circumstance the property shall be shared equally among all the legal heirs of your grandfather, there is no question of sharing of property on percentage basis as per HSA.
Please remember that the society bye laws has got nothing to do with the law and provisions of Hindu Succession act in this connection.