Jj...I can relate.
My sister and her hubby are full up opiate adds. Sis drinks on top, hub smokes pot on top. All day long.
They make it, w help from the state, her go getter son, and Dad. It is not good. It is going to come to a high pitched horrible crash sooner than later.
No advice for your sis from me. I told my sis about the educated help and understanding I got from here is all.
We have to take care of our selves first.
If my sis ever asked for my help it would be tough. My wife already told me, if my sister moved in, my wife would move out.