Pagdi System Transfer Rights

Our flat is under pagdi system in my grandfather's name. He passed away in 1992, but the name transfer is not yet done. He had 3 sons, out of which the eldest one passed away a few years ago. So now the legal heirs are my father, my youngest uncle, my eldest uncle's wife. My father has been staying in this house and paying the rent since past more than 40years. Now that the builing might go for redevelopment, the owner wants us to get the name transfer in single survivor name. Can you please tell us the alternatives. None of us is in a position to pay the hefty amount to the other heirs for transfer. So in that case what can we do?