Forced Opponents - is there a way to reduce the number of players for a game down to two and then force the other six into a game?

[LordStark]

So as some of you know my mod is focused around a Lord - Lord Player who can appoint vassal Lords and primarily has to resist Norse invaders - before eventually crossing the seas with an Army to put them all to the sword.

But I always wanted the "King" and the Royal Army to be present in the game as well. It also occurred to me it would be cool to have local monasteries that are outside of your control. 

What I could do is change some of the factions that are already in game to "The King" and "The Church". But I don't really want them to be an option, I would like them to be present in every single game (I guess the player would only be able to choose 4 player maps).

Is there a way to do this? To make it so that the player does not even get a choice on adding "The King" and "The Church". The King and Church would start out as your allies but eventually I want you to come in to conflict with one of them.   

From the players perspective, they would choose a four player map and be permitted to select a side (either Lord Player of House Player or "Norse") and then set the opponent as the other side. They would then begin the game on a map that automatically had the King and Church included.

[Stan`]

Scenarios can have locked players.