Leafy, how do I even being to help the one who always helps me? You are so much wiser than me but I would feel awful for just being silent when you go the whole 9 yards to help me every time. The only thing I can think of is to give examples.....Hope this helps, even in a small way.
My 45 year old cousin who lives "that type" of life style, has been to jail and continues to go to jail so much, that it's now normal for him. When he started going to jail (at a very young age), my aunt (his mother) always bailed him out. He has never changed, not one single iota. She has stopped bailing him out now within the last few years because my Uncle is going through extreme health issues (my uncle was against bailing him out. Ever.). My aunt and I had a heart to heart one time, it was a brief conversation, and she told me the worst mistake she ever made was bailing him out over and over and over again. I wouldn't even inquire about the drug program as this might give her false hope as well. She knows it exists and if she wants it, she can fight for it herself.
I have childhood friend who is now 41 years old. Most of his adult life has been spent in county jail or prison for such petty crimes. All his adult years are lost in space. It's so sad because he had so much potential. While his mother has stopped bailing him out and even visiting him in prison over 13 years ago, His mother always allows him to come back to live at her home after his stints in lock up. It was and is extremely dentrimental to him. Furthermore, there are so many bad memories in that home (it's the family home for 50 years ) that I feel it regresses him back so much the minute he walks into that door. She does him such a severe disservice by allowing him to live there. It's such a viscious cycle. I'm surprised that he, himself, is not sick of it by now. I often wonder what he will do once she passes on because he has no one after she does.
Now for myself as an example.....
I was never a criminal, drug addict or the such, but I did make some pretty bad mistakes. Nothing illegal, but just extremely poor life decisions (over and over again). The only people that i had that semi-cared about me were my grandparents. They would flip flop on how they would go about helping me. Sometimes they would rescue me but a lot of the times, they would flat out refuse to help me in a harsh way. What really hindered me though, is when they were sometimes in the middle of these two extremes. I'll explain. In these times, when they would tell me that they were not helping me, I would finally come to a place of acceptance and start digging myself out of my own hole. I would be doing good and start making head way, then in the middle of it, they would start offering to help me. I then would immediately give up on all my progress thinking they were going to fully rescue me again. You know what happened next? I lost all the headway I personally was making without their help and lost whatever little help they were offering because they never said that they were going to rescue me, but in my mind, that's what I thought. It was a mixed message. I really wished at those times, that they would have stuck to their word when they refused to help me and just not interfered at all because it only hurt me. They too were stuck in the enabling ways which caused me a lot of harm at times.
I think in this instance, keep going on about your life like this never happened. Do not help or contact her at all. Let her sister know this too so there is no mistake. She is 30 years old, it's either now or never that she starts changing her life. Maybe when she is forced to do it on her own like I was, she will come back to you. I came back to my family in adult and loving way but it took too long. So much time wasted. Do it now. I have no doubt in my mind she will want to reconnect with you again as mother and daughter in the future, but in order for that to happen, right now she needs to know that you are not having this mess. Ignoring this situation could be the best thing you can do for her. Let her learn her hard lessons now. Don't even let her know you are inquiring about her situation. It's probably just not best to inquire about it all anymore because word might get back to her that you were calling around and that might give her the wrong idea that you will help her in some way.
Of course, I could be all wrong, but it's the best that I can do. Sending big hugs your way.