That's got to be tough. The only way she will stay somewhere for a while is to get arrested, but you have to make sure no one will bail her out. I don't know if I'd be able to set her up for that either though, because either way (failing a drug test or having an arrest record) is not going to help her land a job if she ever wants one. And it will most likely create more tension between you two. Sorry, I don't know what to recommend.