After rebelling, you can order your NPCs out into the world map and combine forces later on. NPCs have the same AI as lords on the world map. However, in battle they will listen to you. May be riddled with bugs, will be fixed later on.
rubik said:update 20/6/09 V0.803:
http://www.rayfile.com/en/files/ca4209e8-5d76-11de-a15a-0014221b798a/
Restoration: defeated faction can be restored once a lord of this faction get a town or castle after he switch to other factions. This lord will be the new king of the defeated faction, the defeated faction is restored.
rubik said:You need join a civil war as the third party, you must eliminate the orthodox faction first, then eliminate the noble rebels of this orthodox faction.