Gift deed of property

My father got an property through wilnama from his father and later he demolished it and constructed a 2 storied building which has four portions. My father has four sons, im the elder one and we belong to christian family. Among the four sons to. My father's one son (2nd son) has passed away in the year 2004. When he(my 2nd brother) was alive my father has helped him with some money to start a bussiness (Gas agency delearship on my brothers wife name). Later after few years he passed away due to health issues after that his wife and two daughters has left the house (one portion among the above said property) and they started live individually on their own and taking care of their bussiness and they were not in any type of relation or contact with my familys or even with my father & mother. Later after few years my father fell sick so in his last days he decided to gift deed the all 4 portions in the property as said, 1st portion on my name (elder son), 2nd protion to my brother name (3rd son), 4th portion to my other brother name (4th son), and 4th portion with love my father has gift deeded it to my son (my father's grand son) and he passed away after few days. Now after all this years my 2nd brother's (who passed away and his wife and children left the house after his death) trying to claim the share in property. Where as in my gift deed documents my father clearly mentioned that there wont be any obligations from his sons and their children. So my questions are: 1). Can my brother's(passed away) daughters claim the property now? 2).Dose this property fall into ancestoral property? (We belong to christian family) 3).If my other two brothers have any rights on the 4th portion which my son recieved. 4). Should i have to file any extra document apart from gift deed to prove I own the property. 5). How can I fight the suit which my brother daughters are trying to claim the property? Kindly provide the suggestions on this issues. Thank you. Alex