Father in law's brother trying to claim all FD from ancestral property

Hi My father in law has join FD with his brother as survivor,this FD money has come after selling the ancestral property ,after that my father in law has purchase one house and brother in law also purchase one house Now my father in law has been dead and there is still one FD as survivor option ,which his brother is claiming that his money and bank will give money to him as this is survior FD My father in law have now only mother in law and my wife as legal hire Can some how we can stop him to take money from bank ,please advise