Pagadi system building redevelopment

Hello, I have a question regarding Pagadi System Building's redevelopment. Me, my mother and my father were living in a pagadi system building. Now the building is under redevelopment. My father has 1 brother and 2 sisters. The rent receipt was in the name of my grandfather. For past 15 years, only me, my mother and my father were living in that pagadi system room and we were paying the rent to the landlord by cheque. My Father's brother and sisters are living out of mumbai and they have their own house at their respective residing locations. For the MHADA verification for redevelopment, we had provided the ration card, electricity bill, rent receipts, voter id, aadhar card to MHADA and the verification was done and the agreement is done in the name of My father. Now my Father's Brother and Sisters are asking for their share in this property which is under redevelopment. And they are asking for a joint name in the MHADA agreement. If we don't agree for the joint name what actions my Father's siblings can take against us?