I moved in with my new partner 18 months ago.  He has 2 daughters that live with him full time. One is 18. The other is 21. (Mom moved back to Scotland after they split - girls did not want to move). She said she would come back for them and find a place in the area but she never did.  And now lives with her new partner in Scotland.  
the youngest daughter is easy.  She's pleasant.  Polite.  And happy. And easy to be around.  The eldest is making my life a living nightmare.  She is rude. Arrogant. Ignorant and plain miserable.