Challenging a registered gift deed

My wife belongs to Kolkata and her father gifted her the property (House) 3 months before he expired. Her elder sister (they are two sisters only and no brother) lodged a complain to civil court that the deed is not valid. The husband of her elder sister is a greedy man having enough wealth and try to acquire more. The deed was registered by sitting commission at home as due to age and ailment her father could not go to court. Her elder sister with husband and local people manhandled her and her husband when the went to the gifted house for which a GDE lodged at Commissionarte office. Please tell me can they get the house wheras the lodged all false allegation.