Rightful claim on property

I am the single son alongwith three elder married sisters from my father's first wife(not alive). He has one married daughter and three sons from his second wife. Now he started selling our ancestral land without apprising me. Of my father's share of 11 katha land, he had sold almost 8 katha. Then I decided to secure my share and got the remaining land (3 katha) and ancestral house registered in my legally married wife from my married sisters. Subsequently I got the registered documents mutated successfully. But one day before when I got the property registered, one of neighbours who had an eye on the property got one katha registered in his name. Now my said neighbour stakes claim on the property and pressurising me to back off. Also my father along with said neighbour warns me of dire consequences to leave the claim on property. Additionally, Four year ago he had committed in front of an Sub Divisional Magistrate that he will give 10th part of his property when I had asked for my share. What are the legal options left in front of me?