@ ADane
Essentially, you're proposing a fourth tier and hence the ability to have kings as vassals. There are a few historical examples of kings as vassals in this period (albeit not many). The Staufen (nb not Hohenstaufen, the Hohen- was added by the Hohenzollerns in the C18/19 to give themselves a better claim to the Imperial title) are not good examples, nor are the other German emperors. Yes, more often than not, their sons were termed king of Germany/Italy/of the Romans or even Emperor. But, this was not a vassalage in the sense you propose. They held the title in name only (the only exception being Henry VI who was king of Sicily through inheritance from his wife, but that was a complicated and unique situation).
Actual examples of kings being vassals include:
John Balliol, king of Scotland was effectively a vassal to Edward I of England. That did not end well.
A couple of the kings of Bohemia were vassals to the German Emperors, but the title was reduced to duke for the early part of the period of the game.
The king of Thessalonica was vassal to the Latin Emperor, but this was not really more than a technicality.
The bottom line is that kings in the CK period were at the top of the social pyramid/tree/whatever. Unlike the Carolingian empire under Charlemagne and Louis the Pious, the Emperor did NOT have kings beneath him in the sense of vassalage. If anything, the emperor could claim to be the first among equals amongst the kings. While this situation could be changed, it should require an immense amount of work on the part of the player. Personally, I'd much rather see an extension of the vassalge system under the king than over it. Of course, then modders would be free to switch the top layer of that system to emperors... Everyone's happy.
Essentially, you're proposing a fourth tier and hence the ability to have kings as vassals. There are a few historical examples of kings as vassals in this period (albeit not many). The Staufen (nb not Hohenstaufen, the Hohen- was added by the Hohenzollerns in the C18/19 to give themselves a better claim to the Imperial title) are not good examples, nor are the other German emperors. Yes, more often than not, their sons were termed king of Germany/Italy/of the Romans or even Emperor. But, this was not a vassalage in the sense you propose. They held the title in name only (the only exception being Henry VI who was king of Sicily through inheritance from his wife, but that was a complicated and unique situation).
Actual examples of kings being vassals include:
John Balliol, king of Scotland was effectively a vassal to Edward I of England. That did not end well.
A couple of the kings of Bohemia were vassals to the German Emperors, but the title was reduced to duke for the early part of the period of the game.
The king of Thessalonica was vassal to the Latin Emperor, but this was not really more than a technicality.
The bottom line is that kings in the CK period were at the top of the social pyramid/tree/whatever. Unlike the Carolingian empire under Charlemagne and Louis the Pious, the Emperor did NOT have kings beneath him in the sense of vassalage. If anything, the emperor could claim to be the first among equals amongst the kings. While this situation could be changed, it should require an immense amount of work on the part of the player. Personally, I'd much rather see an extension of the vassalge system under the king than over it. Of course, then modders would be free to switch the top layer of that system to emperors... Everyone's happy.