Essentials of a valid gift under Muhammadan Law
1. The Donor must be Competent:
The donor must have a capacity to make a gift, i.e., he must be a major and of a sound mind. He may dispose of the whole of his property by gift in favour of any person including a stranger, even to the entire exclusion of his heirs. There are no limits on the power of the donor to dispose of his property, as there are on the testamentary .capacity of a testator. The donor’s intention must not be dishonest, as where a gift is made with intent to defraud creditors.
2. Declaration and Acceptance:
There must be a declaration of the gift by the donor and an acceptance of the gift, express or implied, by or on behalf of the donee.
3. Delivery of Possession:
It is essential to the validity of a gift that it should be accompanied by delivery of possession, depending, of course, on the nature of the property gifted. The taking of possession of the subject-matter of the gift by the donee, either actually or constructively, is necessary to complete a gift.
Registration of the deed of a gift does not cure the want of delivery of possession. Neither writing nor registration is necessary to validate a gift either of movable or immovable property. Possession is not delivered then the gift is incomplete, and therefore, void.
In your case other grandson's claim over the property could not success in the eye of law. A gift transfers Doner’s ownership then there in Donee favour