Has Anyone added belt/sash to culottes

I made a version of the culottes but more as a wide leg pant for my 7yo. She wants a fabric jeweled belt as featured on the blog a while ago. But I really think adding a large attached sash that could be tied into a large bow would look great with a cropped cardi or tucked in tee. Anyone have dimensions for a sash belt for a 7/8 kids size?