Examine your headpiece. The plastic band has two little tabs that when pressed in will take it apart. The only problem is that the hair is glued to it. Lucky for us, it's hot glue. (Disney, I expected better than that!) Gently pull off the flower, the hanging braid, and then several inches of the end of the braid crown on one side. I chose the right.
Now, measure your child's head, and subtract 18" from it. Add two inches to that and heat seal the ends by running them over the lit lighter. Fold under the raw edge, glue in place, and then whip stitch it for extra security. You'll need to measure, keep measuring, and fiddle with the other side until it measures correctly. Glue and stitch in place, and then try it on your child's head.
Now, let's talk about attachment. The combs were oddly placed. So I didn't put them where they'd been--I put them on the sides and glued them in place... at first.
But if your little girl is anything like Gracie, this next step will insure that it stays on her head. Cut 1/2 inch pieces--I did 10--of the 1/8 inch ribbon and seal the ends. Put the sealed ends together and whip stitch them.
We're doing double twists that end in a low bun under the braid and securing it that way so 1) it won't fall off and 2) she can't just pull it off. We've made it clear that she'll need to see her teachers for help to get it off if she needs to.