Can cousin claim share in property registered in father's name?

My gradfather verbally willed the property which his mother had purchased to my dad. My dad had two married sisters and one unmarried sister, whom he financially took care of alone. All the three sisters honoured the verbal will and did not contribute towards any expenses or claim anything. Accordingly one married sister and the unmarried sister relinquished their rights in favour of me and my sister after our dad's death. The other married sister is dead and not alive to relinquish her right. Some of her children are claiming a share in the property which was taken care of by my dad and he also rebuilt the house. We are willing to give our cousins the share if they are willing to pay the cost of rebuilding the house with compound interest. Can we legally succeed? They are also claiming a share of the unmarried aunt, even though my dad has financially cared for her and she has relinquished her share in our favour. Can they succeed?