Property Case: Please Help

Dear Sir, Greeting for the day. I want your help in my family flat matter – I am staying in a house with my In-laws. My In- laws are staying here from more than 25 years as their uncle told them to stay here from starting but the flat is on father in-law’s brother name. And now father in-law’s uncle is no more and flat is about to go under redevelopment. So father in-law’s brother is saying I had given the flat just to stay when your financial condition was not good and not for life time so basically if he takes this flat back we will be homeless. We have all records of maintaining the house as society maintenance and everything we are only paying. Electricity bill is also in my In-laws name. His brother has only the share certificate, Agreement and Registration document as flat is in his name. He is real brother of my father in-law who had never thought his brother can do something like this where he can be without home. We tried for compromise and settlement but he is not ready for that as well. Now we have filled the suit against them for the same. But in their reply he is saying he has bought this flat with his harden money and he should only have all rights of the flat. My in-laws were not aware that on papers name is so important and his brother was elder so they used to buy all property in his name only and my in-laws were very innocent not aware about the cruel impact of the same. We are spending sleepless nights I need some solution for the same. How we can prove that my father in-law uncle had told officially its our home as all was oral and there in no written proof for the same. Kindly please help me out which can give us a peaceful life with a proper shelter. Hoping for your reply as early as possible