Yikes ... what a huge responsibility for an older sister. I commend you for taking in your sister. I write a lot about teens so please go thru some of my blogs on my website: bratbusters.com. All free information.

Now ... you are going to have to work hard to keep the lines of communications open at all times. Try not to judge when she is talking to you, just listen and "guide". Avoid the word "no" which is poison to teens. Rather say, "how about ...".

She's going to have to have rules, guidelines and chores so work those out TOGETHER. The more involvement she has in decision making the more likely she is to follow thru with same.

Lisa.