I am sorry you are going through this. I have not been in this situation myself. To me it seems like you need to talk to your sister and set up some boundaries and stick to them like super glue. I understand you love your sister and feel guilty because of her coworkers, but she is not ever going to learn to take care of herself if you keep bailing her out. Maybe tell her that you will help her out only if she is med/treatment compliant. If she is in trouble due to not compling to treatment I would not help her. She will hopefully learn from her mistakes. Hope this helps.