You definately need to get a detailed accounting of their history. My guess is that they have significant histories of maltreatment, and, if so, are a high risk of having Reactive Attachment Disorder. You may want to get your own assessment by a licensed mental health professional who is trained and experienced in treating adopted and foster children and who meets the criteria to be a registered clinician of
The Association for the Treatment and Training in the Attachment of Children .
Generally, children who really have ADHD respond well to medication...if that is not happening, then you need to get a reevaluation. The third and fourth meds are usually prescribed for children with mood disorders, such as Bipolar I Disorder. You might want to take a look at the book The Bipolar Child.
regards