Wow... I didn't know that about ADHD but even still I would not be ok with children having coffee in my care. Or before they come to my care haha. My 2 year son old once had a drink of my iced coffee (my head was turned BAH) and he hated it so now he stays away from it but that is the one experience I have with children and coffee. Caffine and children just do not seem to make a good mix in my head.

I have my fingers crossed for you that it gets better, perhaps ask the parents not to caffinate thier children before coming to care and see if they are better then?