Ugh. that all sounds so overwhelming.
I have lived with addiction and from my experience, your sister will agree whole heartedly with all your requirements and quietly and one by one disregard each and every one. Not all at one time, and not with fanfare, but just go on about her life without regard to your requirements. For me, this made it very very hard to say 'OK, now, now the line has been crossed. This I will not except.' It was just one step away from the last small step and before I knew it I was a miles away from what I had originally thought was acceptable in my life. I felt terribly desperate and confused. I'm not trying to be condesending but you already sound a little desperate. You are already doing things that you don't really believe are in anyone's best interest. Not hers, not yours, not the children involved, yet you feel like you must do them. This will make upholding your boundaries very difficult. You might consider identifying a move out date ahead of time and make sure she knows about it ahead of time so there are no surprises and hold firm. That would be a very concrete boundary that you can hold to without any shades of gray.
Al-anon was also a great suggestion.