I had a younger sister who was definitely indulging in some unhealthy habits. I felt just as conflicted as you and I think you need to use your own judgement. You know her and you know when too much is too much. I know it can be scary and its so unfair that it falls on you to get her in line. Also, I totally get what you mean about not wanting to put more on your parents plates but don’t forget that they are still parents. They want to make sure their kids are ok, no matter what.