My grandmother is refusing to give our rightful share of the family property. What can we do?

My parents left my grandparents house 25 years ago because of the toxic and abusive behaviour without taking anything. They slowly built their lives, living in a different town.

My Grandfather expired last year, and we did all his last duties with good faith thinking that after all these years we'll finally live together like a family.

Earlier this year my parents asked my Grandmother for our share of the property. Which consists of land worth approximately 5Cr, my mother's jewellery which were given to her during her wedding and taken back. And around 3-4Cr of Bank Balance which my Grandmother has in her name which she got from my Grandfather's ancestral property sale.

My Grandmother is refusing to give anything, my father has a younger brother (criminal, murdered hir first wife, divorced second wife, also has a son with his first dead wife) who lives with them. And he is dearest to my Grandmother and she is completely in his favour and refuse the idea of sharing a single rupee with us, and wants everything for himself.

My father talked to a lawyer and he said that if we file a case for the property, my Grandmother will get the right to transfer all the property to whoever she wants (My criminal uncle or his son). Is it true? And is there any other way out of this? Please help.