I had braces and they are no fun, especially in the beginning. I had them as an adult and I truly feel for the younger children who get them because they can be quite painful as well.
My Dr. gave every patient a Water Pik the day we got braces and told us to use it daily. It helps so much with extra cleaning in the areas hard to reach plus it kind of massages the gums which is soothing. I often added a salt or original Listerine to the warm water.
Sonicare is great and can also help soothe the gums. I love my Sonicare.
Keep being diligent with cleanings and help her learn how to manage it. It takes some time to adjust to the braces and new daily habits which have not changed.
Good luck.