Pagdi building now gone for redevelopment

Hello, We had a room under pagdi system in charni road, mumbai. My uncle use to live in that room. He oassed away in 2010. And since thn the room was kept closed. The rent receipt is under the name of my great grand father. Just Before the building was about to go for REDEVELOPMENT I went to the trustee office and paid all the pending rent of about 13months via cheque. I requested for the name transfer in the rent receipt but since my grand father had 8childrens, trustee's office insisted to provide NOC from all the legal family heirs. After that Covid striked and we were unable to complete the formalities....and now the building has already been demolished and now getting redeveloped by a notable developer. The developer called up and said he will charge 20lakhs as for name transfer fee (even though its family transfer). Developer is threatening me saying that he is the landlord now & will take away our room as its not in our name. He wants me to sell it off to him at a throw-away price so that he can sell it off in future & make 100% profit. Pls guide us as how to go about this matter. Regards Kuldeep