How can I add my or my elder sister name in fathers property

My father's doing 2 marriage ,I'm his 1st wife child, we are two sister or one brother from 1st wife. My real mother separate leaving last 23 years from my father. Or my father leaving with his 2nd wife or one daughter, my brother was expired on 2015 or my father -mothers not getting officially divorce. Now our uncle aunty or step mom tried to cutoff our two sisters name from fathers property,please suggest me what can we do for property Rights