NOC from the housing society for the transfer of flat ownership (legal heir after co-owners death)is

NOC from the housing society for the transfer of flat ownership (legal heir after co-owners death)is needed by CIDCO.Our society has collected a considerable amount for CIDCO Deemed Conveyance which is pending after13 years.They stopped acting on it.The chairman himself sold the flat ,the cashier has rented out the flat.They have never shown passbooks,didn't inform us while selling flats,norms were never truly followed.But when we refused to pay maintenance to recover our hard earned amount paid before 13 years,they started threatening us via messages,videos n now they denied to provide NOC though it states about the dues paid by the late member,not us.We read one of the lawyers article stating that "the society can't recover dues from legal heirs forcefully until flat transfer is pending some clause 101,society can't recover if their functioning is not clean".But we didn't find any other content which can prove the authenticity.How to get NOC n amount.