Please help in civil law matter?

If the property purchased by your Father was ancestral you may have to consider the point. Otherwise, If the property was constructed by your Grand Father out of his own earning and the Purchased /Sale/Transfer has been registered during the life time of your Grand Father ,There is no problem. You will have to prove that the property was a self earned one of your Grand Father and not ancestralHoweverr you will have to wait till the court decides the matter .