My 8 year old still uses every trick in the book to delay bed time, but vomiting? That's dedication to your goal!!

Are you sure she's not actually ill? I've never heard of a kid who can vomit on demand. Or is she getting herself all worked up to the point of vomiting?

I don't have any really useful advice, sorry. We worked on the theory of anticipating all demands prior to putting DD to bed - off to the toilet, small drink, story, cuddle, back rub... off to sleep now. Sounds like you are already doing all of that. If DD comes out we quietly tell her to go back to bed and ignore any carry on. In all honesty, it seems to work... although she'll still try us a couple of nights a week!

DS is six and he plays hard all day. We put him to bed and he is asleep by the time his head hits the pillow - bliss!!