Transfer / sale of property by grand children in cantonment

We have a house which is in my grand mothers name as per the general land Register in the cantonment board .My grand mothers expired leaving a unregisterEd will only on her three sons name which is not on stamp paper in the year 1967.The grandmothers sons have expired and we are six grand children left who wish to sell the property .There is no dispute within us .Now is the will valid as it is not on stamp paper .And can the property be sold directly with out transferring the property on the grand children's name in the general land Register extract.