Braid Question

I have a question. My 3 daughters are half black but don't have what I would call 'normal' hair. Not to say that all mixed people have the same hair but most of the ones I know have stiff, kinky hair. My girls have very soft, spiral type curls. They love me to braid their hair, especially in the summer. I like it too because it's much easier to handle that way than trying to brush out every day! According to that nice chart I looked at that someone posted, my oldest would be a 3B.2 hair type with my other 2 girls having progressively looser and softer curls. My second girl has MUCH looser, more 'wavey' curls and my youngest I refer to as "curl challenged". Her hair is short, soft, fine and barely curly. But she is only 3 so she may get curlier later on. Anyway. I digress. My question is, when their hair is braided, I 'think' I should use something on their scalp and roots to help protect them and keep the hair strong and healthy but I don't know what. Most people have recomended products for much drier, kinkier hair and I feel these would simply be too heavy for my girls' hair. Does anyone with this hair type use anything good they could reccomend? Any suggestions are helpful! Thanks!

BIOSILK makes a serum  (Silk and Shine). It is slightly expensive but a little goes a long way.  I have had the same bottle for about a year and I use it fairly often.  A quarter sized amount works great for my extremely thick curly hair.  It does not provide any hold or definition, but it is great for braids or buns.  When I use it, I comb it through my damp hair, and pile it up on top of my head into a tight bun.  When I take it out, it is SOOOOO soft, smells great, and feels a ton better.  Plus it SHINES like you would not believe.  This stuff seems to be great for what you need.  It is perfect for those who heat style as well!  Which is why I'm sure that for your girls, if they are in the sun, it will protect them beautifully.
The serum has an almost oily texture, but it is not for ethnic hair, its for everyone.  You can use it on wet or dry hair, and they even suggest it for your skin! 
It is honestly one of the best products I have ever tried.  It just doesnt provide my loose curls/waves with any hold, but it conditions them beautifully. 
You will only be able to get this at fine beauty suppliers though.  Anywhere they sell salon products you can get this. 
Hope this helped.
~Christine
PS - Make sure you shake the bottle very well before each use!

Coconut oil, olive oil and jojoba oil are all great. Or you could get some shea butter and melt it and cool it a little before using it on your little one's hair.