Share Certificate Transfer

Dear Sir, 1) I have purchase a SRA flat in dharavi area on 7th February 2019. I have paid stamp duty registrations charges and also paid SRA registration charges and availed NOC from SRA authority. 2) The owner was designated as treasurer of the society and his relative was secretary of society, the agent was secretary son and the home loan was done by owners son who is an employee of bank. 3) On 14th March the owner and agent asked us to pay 25000 towards share certificate transfer charges and we paid cash accordingly but on receipt they have mentioned as donation and both names( owners and my name). original receipt is with me. 4) I was in constant follow-up (from march 2019 to march 2020) with secretary, owner and the agent but every one assured me of getting it done asap. The secretary said the transfer process needs approval in AGM so you need to wait for sometime. 5) In march 2020 due to covid lockdown all activities were at halt in this period on 30th April the owner death happened and post opening of lockdown in month of September 2020 i again approached the secretary for share transfer process. 6) The secretary demanded 15000 more to do so and we agreed to pay by cheque but the secretary refused to take and started argument. 7) we have done written communication with society secretary and owners son on several occasions. we received letter from society mentioning that i need to fill and summit form 20 for the share transfer certificate. on this note i gave they form 20 to owners son duly filled for signature but he did not respond to any letter given by me. 8) Currently the society secretary is not responding to us or helping us to get the share transfer certificate process and the owner son not ready to give signature of his mother and his brothers and sister is claiming the right in the property which i have brought from his father. Kindly advise on below 2 subjects: 1) Can family members (Son and Daughter) claim their rights after his father has legally sold the flat. 2) Where do i go if society secretary is creating problems to help us in doing the share transfer certificate process. Thanks & Regards