Asked in Property
It is valid. one can sell his undivided share in a property without the consent / knowledge of the other share holder.. you may contest the same on other grounds i.e. malafide intention
Agreement was registered in both the names of your father and uncle, but about sale deed. If the sale deed also reveals both the names then Gift Deed has not value and you can file a suit for declaration for cancellation of gift deed and for your half share.
I think your uncle may have given you wrong information, when it is in joint name consent of both should be obtained, even if your uncle has transferred to his son your uncle has right to transfer only 1/2 of the property, assuming that he has transferred whole of the property then if you challenge that deed in court you will definitely get the share of your father. so better first get all the revenue records verify and then file a case.
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