Daughter Right on Father Property

My Grandfather (still alive 2017 and fully active physically and mentally) inherited a residential property in Delhi through will from his father. My grandfather are 2 brothers both got 50% share. Later my grandfather settled/bought the share of his brother and got a release deed executed from him. My grandfather has one son and 3 daughters and approx 2 years ago he gifted his entire property to me (grandson) with no objection from my younger brother. We are 2 brothers (grandsons). Now one of my father's sister (not yet aware of this gift deed by my grandfather to me) asking to get her share in property, while other 2 father sisters are well to do and not supporting 3rd sister in asking the share from my alive grandfather. I need to know, is the gift from my grandfather to me is valid (we have paid all the gift duty as per the govt norms), was their any mandate to get the No objection from other grand father class 1 legal heirs for the gift that has happened, can this give be challenged by by father's sister now, and last can she has claim on my grandfather;s property.