I'd like to jump in here and mention that if your daughter's hair is 4c or Z pattern, a curl definer won't make curls that aren't there. Z pattern hair, which turns at sharp angles rather than coiling, forms a lovely fluffy cloud of hair rather than a head of curls. It's good to keep in mind that many people have more than one type of curl pattern.
The key to all loose styles looking great, regardless of the curl pattern, is enough moisture. There are a lot of fabulous conditioners around, my personal favorite for dry hair is Aubrey Organics Honeysuckle Rose. Choosing an excellent conditioner and then adding moisture daily keeps the hair in great condition. Adding a small amount of coconut oil a few times a week improves hair elasticity and makes a big difference in overall hair health.
If she has curls that can be defined, some wonderful products are Darcy's Botanicals Natural Coils Curling Jelly and Blended Cutie Jelly Cream, Down and Out or Happy Nappy Styles.
You can find a video I made on daily care for loose hair here: http://www.youtube.com/happygirlhair
. You can find product reviews and recommendations on my site Happy Girl Hair
. I have one daughter with 4b/4c hair and one with 3b/3c hair.