Adam is the boss of Ben, Carl and David. Ben is the boss of Edward and Frank. Carl is the boss of nobody. David is the boss of George and Harry.
A word or short phrase that would distinguish Ben and David from Carl as they relate to Adam.
Adam's [WORD] are Ben and David. His other subordinate is Carl.
If there is not a single word, a very short phrase might work.
Edit: Answer a few questions:
1) Is Adam a CEO:
Adam is not necessarily the top level, although he could be.
2) In what company? Under what structure?
Private sector business.
3) Why do you need this word or phrase?
It is for a section title/header for a report that has information about how the direct reports are keeping up with managing the people under them. (How well their 'children' are keeping up with tasks related to their 'grandchildren' in the hierarchy)