How to get back registered property back from relatives

My father had received some land in Kerala, after division of the ancestral land between him and his siblings. When the land was divided and registered in individual's name, he was in good terms with his siblings. Hence the registration papers of his land were kept with them, i.e. in Kerala, whereas we are living in Ahmedabad. But later on due to some family issues, the relations went soar. Now my father has expired, but the land's registration papers are still with his siblings in Kerala and they are not returning it to us. I want to collect those papers from them and hand it over to my mother. Kindly advice, what should i do in such case. Also let me know, if it is possible for them to acquire or sell my father's land without our knowledge or consent.