You're a great mom. I tried to read carefully. And I understanding the problem is excessive shedding and/or lack of definition? Thanks for telling us properties because that is helpful. The one thing I suggest you figure out is protein tolerance. Not having the right moisture protein balance will cause issues. This is something that takes experimentation because not everyone's needs are the same. Example My hair only likes certain kinds of protein and only as rinse outs. Not strong protein treatments for me. And no protein leave ins for me either.
You might try a Reconstructor and see how that does. Pts should generally be followed with a deep conditioner to get the balance back. One way to tell is get everything he uses and organize what works well, what doesn't and why. Then look for common ingredients for what is not working. That in time will show what your hair hates and what to avoid. It could be aloe, glycerin, coconut oil. If more people did this they would save so much money on stuff that doesn'y work.
Also you didnt say that he was sealing after applying his li. A little oil might help keep the moisture in his hair.
Transition your mind before you transition your hair.