Supplementing your daughter’s diet with green superfoods may indeed add some absorbable forms of nutrients into her diet. There are many exceptional greens products on the market unfortunately not all of them are that palatable.
I personally recommend the use of Designer Physique's Greens Boost in terms of its taste and formula. I find that adding the powder to my water bottle with a squeeze of lemon makes this powder highly palatable. The lemon juice can also hide the taste of some of the less palatable products on the market.
I have also found that in a milk-based smoothie or juice the taste is great too. You may also wish to look at other builiding foods like oats and the use of fatty acids in supplementation to aid your daughter to gain weight and support her nervous system.
Please let me know if you need a referral for an experienced Naturopath to aid in your daughter’s treatment.