I thought about an overall commander as a seperate squad for two points. The overall commander himself has no special abilities, but his squad includes all the specialists like medics, balloonists, cooks, archaeologists (to solve side quests for example), heliographists (I am not sure if this word exists), the officers wife, missionars, war correspondents an so on...
All specialists may or may not add special abilities or bonus to the overall commander.