The Hindu Undivided Family property is owned collectively by all its members, and the Karta manages it on their behalf. According to the Hindu Succession Act, 1956, the Karta has the power to alienate huf property for legal necessity or family benefit with the consent of all adult co-parceners.
The validity of the sale deed depends on whether it was executed for legal necessity or family benefit, and whether all adult co-parceners consented to it. However, if the sale was not for legal necessity or family benefit, or if all adult co-parceners did not consent to it, the sale might be challenged as invalid.
In the scenario described, if the Karta executed a sale deed conveying the huf property to the wife and acted as a representative of other co-parceners who attested as consenting witnesses, the validity of the sale would largely depend on whether it was for legal necessity or family benefit. If the sale was for such a purpose and had the consent of all adult co-parceners, it could be considered valid.