1. Share of property of a minor can not be sold by her guardian/mother with out the approval of the local District Judge,
2. District Judge is the custodian of properties and share of properties of all Minors whose said properties are coming under his Jurisdiction,
3. The District Judge approves shcu sale of Minor's properties only for the welfare of the concerned children,
4. In view of the above the instant sale of minor's share of the property by her mother to your grandfather was illegal hence invalid,
5. It will be prudent on your part to settle the matter with her amicably in your interest.