1. The Will of your grandfather is required to be seen,
2. In the Will , had he given living right to our grandmother or willed he entire property in the name of her?
3.If the entired property was willed in her name then your grandfather can not furtherwill hat after her death her sons will get the property. In this can your grandmother had not received the title of he property but only he living right during her lifetime,
4.Moreover, if no probate was taken on the said will and also if that will is lost, then it has no value at all,
5. All he legal heirs of your grandfather including his daighter has right on your grandfather's property,
6. Without he consent of your father, the said property can ot e sold,
7. Your father ca talk to he developer for alternate accomodation if redevelopmentt is found to be benificial for him.