I hate to go against the general opinion here, but I still feel sympathy for your eldest daughter. Yes, her swearing at you is wrong and everyone, whatever their age should be able to go about their life without being sworn at or swearing at other members of the household. But.....your comment about 'we would have done the same for her if she was pregnant' disturbs me a little, and it does come across almost as praise for the 17 year old getting pregnant. I am sure you are doing what you can to help the 17 year old, but it is not ideal having a child when you have never even had a job let alone paid your own rent. I am not blaming you or your youngest daughter, but I think the 20 year old needs some slack here, she sees her sister getting all the praise for being a good mother, getting the best room etc. you still seem to be blaming her and to be honest I think you need to act the adult and take control, politely tell her that swearing and shouting will not be tolerated, but when you have this conversation, do make sure that you dont shout at her. ( we have all done it!). Not trying to tell you that you are wrong, but just try to see it from her point of view.