Before going to reply your query , You should know the following laws under Muslim Law:
- As per Muslim Law "Gift is a transfer of property where interest is transferred from one living person to another, without any consideration. Further Registration is neither necessary, nor sufficient to validate the gifts of immovable property. whether it is attested or registered or not, provided that the delivery of possession has taken place according to the rules of Muslim Law.
- Under Muslim law, all gifts are revocable before the delivery of possession is given to the donee. It will not make any difference that the gift is made to a spouse, or to a person related to the donor within the degrees of prohibited relationship. The fact of the matter is that under Muslim law no gift is complete till the delivery of possession is made, and therefore, in all those cases where possession has not been transferred the gift is incomplete.
- According to the Hanafi School, with the exception of the following cases, a gift can be revoked even after the delivery of possession. Some of exceptions :
1.When a gift is made by one spouse to another.
2.When the donor and the donee are related within the prohibited degrees.
3.When the donee or the donor is dead.
4.When the subject-matter of the gift is no longer in the possession of the donee,
5. When the value of the subject-matter has increased.
6.When the donor has received something in return (iwaz).
Now under the above rules of law come to your case :
The possession of the property was handed over to the donee during the life time of donee ,so it is not challengable.
Further Mr A was having his legal right to gift/ transfer his property to anyone as per his wish even to a non blood relative. So , it is not challengable .
Thus, finally the challengable aspect is only the age of Mr A and the witness of the Gift Deed i.e. the Gift deed was not signed in the presence of any family members of Mr.A. It means , he has gifted the said property to the donee under the influence , force and due to unsound mind being 80 years old.
Therefore , daughter of Mr.A can challenge the said gift for getting the relief in her favour after filing a suit of Deceleration, Possession & Mandatory Injunction . Sure , she will get her share as per Muslim Law.
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