What to do there are property issues between relatives

My grandfather bought 1 acre land in 1971. Later he died. He has 2 sons and 3 daughter. My father and his brother asked me to take the land and give them money because they were in debt. In 2011 the land was registered on me. Both said they will take care of their sisters if any problems arise. This were written in registration documents. My father has 5 children. One of their daughter sued on me for claiming the property. Now my father and his brother say that I had to take care of it. Can I sue a forgery case against them.( My father and his brother)