Very disrespectful and tude 7 year old. Advice/opinions?

[mom-in-alberta]

I would issue a final warning to the parents about her behaviour. List very clearly the things that she has been doing that are not acceptable in your home. Make it known that you strongly recommend that she see someone to discuss her lingering struggles with the separation of her parents.
Give them a specific "needs to improve by" date. And if they don't even try to make things better, then turf them. It's sad, but how much more can you do? And I would worry about the wellbeing of the smaller kids.