hello literally i need a legal advice if u help me out ill be very thankful to you.so the problem …

 i need a piece of legal advice if u help me out ill be very thankful to you.
so the problem is my father was married to my mother is his first wife, we are three brothers and four sisters. my father married the second time in 2006 or 7, so I have three more brothers from my second mother.we are 10 siblings, literally, my mother give lots of sacrifices and spent his time with my father till we matured, now my father is trying to marry the third time and i don’t know why my father is principal like an ordinary man but his behaviour is totally bad to us as compared to my step mother and his sons.so now he is trying to marry third time with a lady which is the daughter of our village landlord. the landlord of our village is totally paralyzed or we can say that he lost his ability to recognize anybody that’s whys he is doing nothing.if he is able so he may not allow his daughter to marry a man who have already two wives and 6 sons and 4 daughters, but his sons and daughters are getting money from my father since one year.they are our relative, they know everyone in my family but after that, they are doing this maybe they are trying to take revenge of any mistake which we surely not done.me and my elder brother study in university my two elder sisters are graduate and my one sister is disabled but she is fine, and my both little brother and sister is study in eight class.we don’t have any kind of financial support so if my father get out us after his third marriage so i don’t know where we go.we don’t have any kind of support from my mothers family.we are totally stuck in between. my mother did not want third married of my father because she know what kind of my father is how she faces his bad behaviour to us only she knows.please advise us if u don’t so may my family take any wrong step thank u.