Who will be the true owner of the property ??

Sir, This is a matter relating to my Grandmother & my father.... In 1953 my grandfather and his younger brother purchased a plot of land in Guwahati but in the name of my Grandmother(Chitha mutation but not registered) she was just 13 years old at that time..Then they lived happily in Hindu joint family..In 1987 my father built a house in this land where we are residing now... In 2004 My grandmother with the help of my uncle filed a suit against my father to vacate the land giving various false claims in public...In court She contended that the suit land was her self acquired property providing only The jamabandi copy of chitha mutation and her own witness to prove that she is right....nothing else....The brother of my grandfather who originally purchased the land had his name in the land document, so he claimed 50% of the land and gave witness from our side that it was purchased by my grandfather and him....But the trial court gave judgement in my grandmother's favour declining 50% claim on the basis of Chitha Mutation copy and her own witness.....now in Gauhati high court Our lawyers argued that From where she got money to purchase the land....In lower court she had given no documents or witness regarding her income or self acquired property....Now kindly inform me that Is there any other substantial question of law can be asked at the time of hearing??