Need advice on property division

I am a Muslim by religion. My grandfather married another woman (after the first wife died). The first wife has 4 children and the second wife have 3 children (two males and one female) of whom the eldest son has expired. My grandfather had made a will wherein he had equally distributed the property amongst his children but the will(unregistered) was torn and hidden by children of the elder wife. The first wife's children received 4 acres of property and distributed among themselves and I don't want to interfere with it. I am one of the sons of my mother, I have a younger brother too. My mother is the child of the second wife and she has an elder brother (the eldest has expired). Now the property which my grandfather bought had 10 guntas land, 14 guntas agri land (bought), 2 houses(one ancestral and another bought it), 9 guntas agri land(ancestral). Now the two houses were registered to the eldest brother by grandmother around 20 years ago and both the houses have loans due. The 14 guntas agri land was bought by my grandmother and a bit was gifted by her husband as marriage bond(Maher) which my grandmother registered to the elder brother(2nd brother who is alive) 15 years ago so that he can take care of my grandmother and the 9 guntas agri land were given to my mother. The 10 guntas land was sold during my mother's marriage and the amount was equally distributed amongst the 3 children. Since my mother's elder brother is not taking care of my grandmother, my mother has decided to take back the property which belongs to her so that she can take care of my grandmother. How can we(me, my brother and my mother) proceed to take back what belongs to us? Is it still possible as it been a long time since it was given to my maternal uncles by my grandmother? Even my grandmother is willing to proceed with this. My grandfather expired in 1991. Thanks.