@whatohwhattodo
It's difficult but whilst they still have capacity (by the letter of the law) there is very little that can be done. I worked for the ambulance service for a while and your sister is not alone in doing what she's doing.
Largely people do engage eventually. It just clicks. Or they become physically unwell and it hits them they need to make a change.
Sadly with PD you're 8 times more likely than the general pop to end your life. Which is a scary statistic and why I end up in coroners semi regularly.
In the grand scheme of things, and sorry to be so clinical, overdoses that are self reported mean she's a moderate risk. It's a very push/pull thing she's doing - help me/don't help me. I'd be trying to get to the bottom of what function o/d has for her and finding alternative strategies and also laying out what things like dialysis are like. Unpleasant, painful, life long, transplants, rejection etc etc. Also meaningful activity like work, education, volunteering is often a big help.
Sometimes it just takes a long time though. Sometimes it takes simple maturity.
Services need to do more to engage people but it's excessively challenging at times. Most CPN in our area have around 40 people on their caseload in the community to manage.