Property dispute

Hi Sir, I am pursuing my B tech .My father was an Singareni Employee and was expired in 2009. My paternal grand father who is alive has 3 sons and 2 daughters . My father is the eldest son and two daughters got married. My father's elder brother took his share and is doing his business. Younger brother is doing some private job and got the entire property registered under gift registration by his name after my father has passed away.Actually i have two siblings sisters who are elder tome. One sister got married recently and my grand parents has given nothing for her marriage and dint even allow us to do at their home .Now they completely avoided us and wrote entire property to their younger son.Can you please let me know what all my rights would be as their grandson to get back my father's share .And what would be the process if i proceed legally? please kindly inform me the details to proceed urgently.sir i have written you my problem so the advocate of my fathers brother has registered the entire properties to his name and the advocate is telling me that legally you cant get yours fathers share & if you are close to yours grand father & grandma they will try to give you some of the it true sir?.to send them the legal notice what should i have? Kindly inform me urgently sir.sir one thing sir:)