Re: How to stop a girl from dancing w/ you but keep her in the set?
Try bringing in another guy to take her while slipping behind another girl. You could also move the HB6 onto one leg and bringing another girl onto your other then quickly slipping off the HB6 and onto the other.
Really, it's all about practice. I've had this happen to me plenty of times and it takes work to be able to pull it off smoothly but it's quite possible.
You could also just tell her you don't want to dance with her. It doesn't have to be a big deal or create a scene. Just whisper in her ear (I'm sorry, I kind of just want to dance in a group not with just you). You can still dance with other girls then as she most likely will take the hint that you just weren't interested.
You are the prize. She needs to earn it.