Ok, good to know! I am looking at the tuff riders since they are inexpensive and knowing my child, she'll be off running through the turnout or romping with the resident dogs/chickens/cats at the barn as soon as her lesson is over, with zero regard for how filthy she's getting. I'll order her a size 8.
We're trying tall boots for her to give her some extra support as she has defects in both legs. Stumbling across winter tall boots in her size for dirt cheap was perfect since if they don't work out, she can go back to paddock boots and I didn't spend a fortune.