No ration card means no rights to purchased property ???

Hii, My father purchased a house in mumbai slum area in 2013 from my grandmother. All paperwork i.e sale agreement, electricity, gas bill and the house is done and in name of my father. Only ration card is in my grandmothers name. We tried to change that before. But my grandmother had mentioned one of my cousin brother as her son in ration card. We removed his name. Now the ration officer says, the name of my father is just below my grandmothers name who is the holder of ration card. Officers say he sees scribble on my father name. The relation is proper as son in law. He also says that you can not get the property without ration card being in your name. Doesn't matter if you paid and made agreement. He also refuses to transfer the ration card to my fathers name and also refuses to create a new one in my father name by discarding the old one. What is the law ? Does ration card have that power to overthrow purchase agreement and can my father be able to make a new ration card ? Help me please