Gift deed of ancestral property

Sir we have undivided ancestral property, in which my grand mother, my father, and his younger brother (Uncle) is the legal heir, as my father was not in good terms with his brother (Uncle), my grand mother was staying with him for some time in those day he had asked my Grand mother to gift deed her undivided portion and a registered gift deed was executed between them,where she stated in deed That my portion I am gifting to my younger (Uncle) son by way of love and affection, no consent was taken from my father even we were not informed about this. and we came to know all this after the death of my grand mother and my father. Sir i am bit confused my questions as follows 1. can my grand mother gift deed her portion to only one son in undivided ancestral property without consent of other legal heirs. 2. even my father's sister was not considered in this and she is also one of the heir but she says that she had given oral consent in front of city survey officer saying that she releases her rights from this property and signed in the city survey officers register book , what is the legal way to make release deed. 3.what remedy is for us to divide the property equally in all of us. should we go to court if yes on what grounds. 4. if my Uncle want to sell his portion can he sell without our consent as it is undivided property and we both as staying there. Thanks