I have a Thal major and a Thal minor child.
Typically, a thal major child would vomit after each meal when he/she reaches the age of six months (I have read somewhere the medical reason for that and will try to get that information). My daughter had a projectile vomit after each meal when she was six months old; until we started the blood transfusion. She attained regular weight soon after the commencement of blood transfusion and eats okay.
My son is not a good eater and I am not sure if this is related to thal minor. I guess every child is different in his/her eating habits. We never looked from thal point of view. On the contrary, we have seen many thal major/minor children eating well.