Grandfather divided property equally now uncle trying to take it all

My grandfather has distributed his property equally to his 3 sons(including my father) , and after that my grandfather lives with us. Now after 5 years both of my uncle's are trying to capture my father's property . My father is a crpf inspector posted in j&k and currently i am completing my graduation living outside city in hostel, so my mother and grandfather lives alone in house, now the situation is that they are trying to lock our house again and again and demanding that it is our house now the problem is that we don't legal papers of our house as it is still in name of my grandfather. What we can do in this if we want to get rid of it?