It won't be difficult to find a chainring/chainguard with approximately the same diameter as you need. The difficulty will be finding one with cutouts for fasteners that match the pattern on your daughter's bike.

I would focus on getting one that will fit and then plan on drilling the holes in the chainring/chainguard to fit your daughter's bike. It won't be difficult to do.

It is a shame that bicycle manufacturers stopped including chainring/chainguards. Without them, the sprocket teeth are exposed and, as you experienced, dangerous. To say the least, they chew up the rider's pants cuffs.