I almost have the exact same ethnicity as your daughter! And our hair is very similar. I would recommend to stop using the keratin line. This acted like a protein in my hair and dries it out to a crispy hot mess! Instead use something with oils or butters. Treseme naturals is my personal fav for a cheap conditioner. To make sure she keeps her curl definition, finger twist the curls. It took me a little while to learn, but now I can finger twist my entire head in under 5 min. There are tons of videos on YouTube explaining this method so I would watch a few, it seems to work on every hair type. As far as hairstyles, instead of braiding, just try twisting. You can fake a French braid look with twists and its super easy!
Love my auburn 3b/3c curls!! Favorite products are Treseme Naturals conditioner and DevaCare ArcAngel(<---miracle for definition!) I really just want to GROW MY HAIR OUT!! It's not really working...