More than 7 vassals

I was deciding the distribution of realms in my campaign (a small principality) when I discovered I had really more than 7 possible vassals for the prince. Some of them I can join into greater domains so I end with 7 vassals but still…
… how could you simulate something like the 26 imperial provinces from Old Imperial Rome? (see The wikipedia says “An imperial province was a Roman province during the Principate where the Roman Emperor had the sole right to appoint the governor (legatus Augusti)”. It sounds like governors were direct vassals of the Roman Emperor. Perhaps the Empire wasn’t divide every time in 26 provinces, but I’m sure at any given point there were more than 7 provinces “active”.
What do you think?

Carlos, there’s a few ways you could handle that.

  1. You can join some of the vassals into greater domains to reduce the number of vassals directly reporting to the prince.
  2. You can give the prince a proficiency or custom class power that increases his permitted number of henchmen.
  3. You can allow vassals that are not henchmen. If you allow vassals that are not henchmen, then the vassals could have to make a loyalty roll for every boon requested of them, and every season, to see if they stay faithful. This could result in a large principality where, at any given point, some of the vassals are rebelling – a state not unlike the late roman empire.

Great points!
Option 1 I had used, but I can join so many domains into greater domains.
Option 2 is very interesting. Is there currently any proficiency that works that way?
Option 3 I really like! Indeed, vassals rebelling here and there frequently could be extremely funny (although not for the prince) in game.
Food for though. Thanks, Alex!

Republican Provinces: you had an ad hoc mix of big Roman patrons (the Pompeys in Umbria, the Aemilia Scaurii in Lombardy, etc.), local Socii (self-governing allies), client tribes and kingdoms, propreatorian and proconsular provinces, and the various minister-without-portfolio ‘special magistracies’ Pompey was so fond of. Lines of authority were a hot roiling mess of ties, obligations and exemptions. To represent this in game terms you could have certain areas as clients of particular senators, while others were vassals of the Senate of Rome as a corporate body. Why two consuls (and later three Triumvirs)? So the Senate can have more vassals, of course.
Early Imperial provinces were IIRC divided into older Senatorial provinces which theoretically answered to the Senate; newer, more militarily volatile, Imperial provinces where the Emperor and his legates(?)/prefects(?) took charge; semi-autonomous client kingdoms (much of Asia Minor) which were technically Friends and Allies of the Senate and People of Rome; and personal fiefdoms like Egypt.
In game terms: after Actium Augustus takes the Senate (and all its vassal jurisdictions) as a single corporate vassal. Of course, he disguises his new de facto authority under the old forms… He also establishes personal relationships with many of the eastern principalities in his capacity as ahem First Citizen of the Republic.
Eventually the Empire found the 26 provinces system too unwieldy (and the military borders too prone to revolt) and modified it into a rationalised Tetrarchic system of praetorian prefectures, diocese, provinces and local districts. As I read it this is pretty much the ACKS vassal system in operation… I expect the Byzantine Thematic system worked in a not-dissimilar manner.