8 is like a mini adolescence. It's a wacky age.
I would tell the parents that if they have trouble with DD, they can call you and you will pick her up. And make sure that DD knows you mean business and you WILL come get her or you will not allow her to do sleepovers until she can behave with others. Before she goes, remind her how she is to act and how bad behavior will not be tolerated and what will happen.
When my SD was 8 or 9, we had one really bad day where she was misbehaving and it was so bad (in our home!) that we called the other girl's dad and had her go home. SD never let it get that bad again.
My SD, and to some extend DD now, too, is the type of kid that is just larger than life. Other kids walk. SD dances. Other kids wear jeans and tshirts to school. SD wears tutus and knee high socks and colorful shoes. Etc. It was a long struggle to get her to realize time and place and how to rein in some of her natural tendencies. It was not just one thing, but working with her over time. No talking in class. No running in the hall. Chorus and theatre did her good - an appropriate outlet for this. Heck, even taking your DD to the park to run off steam before seeing a friend might be a good idea.
You might also invite the friend to YOUR home to see how they interact and work on DD's behavior around friends.