As a grandson, am I entitled to a share in my grandfather’s property? If my father is planning to sell it, can I legally stop the sale?

Under Indian law, you, as a grandson, are generally not entitled to a share in your grandfather’s property unless specifically included in his will. Your father, as the legal heir, has the right to sell the property. You cannot legally stop the sale unless you can prove you have a valid claim to the property, such as through a court order or a legal agreement.