Ancestral Property with No property documents - How can we register ?

My Grandfather has left a house without any will which was earned by him. That leaves 5 legal hires. Out of these 5 legal hires. Only 1 of the heir is living in the property for the last 30 years and continuing to live even after my grand father demise - 8 years backNo property documents are available even after searching the registrar records since it was brought before 1970In this case, n1. how can the property separation and records mutation to the legal hires can happen ?n2. Since there are no property documents, with law of adverse possession can the only heir who is living in the property since 30 years claim the sole ownership and register the property on his name with the proof of residence and demised grand father's joint identification record (ration card) ??