I'm not a mom but maybe I can help.
Have you tried detangling her hair in sections? With our hair type it's best to do everything in sections.
Also...I personally would stay away from products in the "ethnic" aisle. Most of them have ingredients that do not moisturize or nourish our hair.
Try co-washing her hair with something like Suave Naturals or V05 Moisture Milks.
After thoroughly detangling it's best to not manipulate her hair too much. So if you can keep it braided or twisted up that can help with retaining growth.
ETA: Hopped on my laptop to further help you...:laughing
Ipod typing is annoying!!)
But yeah do everything in sections....umm if it helps i can tell you my regimen and you can see if you can incorporate that into hers...?
I have both curly AND kinky hair on my head so...what i do is....i comb my hair every 3 days in the shower drenched with water and conditioner with a shower comb....a widetooth comb. I never use fine toothed combs and i NEVER comb my hair dry.
On the weekends is when i shampoo my hair in halves to thoroughly cleanse my scalp. Then i rinse thoroughly, add my detangling conditioner(a thick creamy conditioner)....and when its slippery enough i section it into 4 sections.....then i detangle with my shower comb....starting from TIP to ROOT to prevent unecessary damage. Do that for all 4 sections. You can rinse it out as you go or rinse all together in sections...some ppl do all of this in twists or braids....i use hair clips.
After i detangle is when i put the deep conditioner in and bc i'm so impatient....it rarely stays on for more than 30 minutes.
Midweek is when i co-wash (conditioner washing) and finger comb.
I usually wear wash n go's but sometimes i'll put my hair in twists and they last me a week. On the days i'm not washing...i spritz with water and add a moisturizer.
Some people like Shea Moisture's Curl Enhancing Smoothie you can get a Target, some people use Shea butter, some people use leave ins...which is what i do. I like Oyin Handmade's Hair Dew...smells like cookies and is very yummy to the hair! She would LOVE it! After that i use an oil to seal in my moisture....i like to use Extra Virgin Olive Oil, Coconut Oil, Sweet Almond Oil or Castor oil....i either pick one of these or i blend some of them together and use that.
I hope this helps. Basically when dealing with black hair...we need water and a moisturizer and an oil...and do everything in sections....it makes it a LOT easier!
I hope i've helped somehow.
CURLs has a fun kids line if you would like to try something she would absolutely fall in love with....all their stuff smells like cake!
Hopefully someone else will chime in.