Thanks for posting this, it is the situation we are facing with a slight twist. AD lives with her mom, the enabler and another sibling, a non enabler. AD was kicked out of dad and step mom's (me) home for not following rules.
I have come to the realization that there is no answer as to what to do about the enabler. You can show them all the articles, forum postings, advice you can find to back up how enabling is hurting the addict but in the end, it is the same as an addict getting help. It has to come from within. The enabler is addicted to enabling. It's extremely frustrating!