Just on my post which may have come across as completely heartless... Obviously you want to determine that the new house is a safe place for her to be. If there's any kind of issues that would mean she wouldn't be safe, then I wouldn't say completely cut her off.

I know you care for her welfare and will do the best thing. I hope I just came across as saying there's a line in the sand where looking out for her becomes detrimental to the rest of the family and from outside it looks like she's crossed it. And she needs to learn the consequences of her actions.

I was one of the kids left dealing with the drama of an older sibling that nearly did my mother in and ended my parent's marriage. The relief after he left and knowing he couldn't come back to arbitarily disrupt our lives (no house key) was immense. It came down to Mum making the hearbreaking decision to ban him from the house (not our lives) for the rest our sakes. So maybe that's why I seem black and white about it.