As example: Add events that giving us cbs to place a relative to enemy throne if we got royal marriage and they are at regency. Accepting this will break royal marriage, reduce relations by 100 and give us cb with target of placing relative for %20 warscore requirement. If successful relative of yours with age 18-23 will be placed on throne with 50 legimicy and you will take prestige of enemy side
or:When truce from huge war ends there can be event giving both sides "force union" cb as nobles ask you to take over their king and they promise you loyality if you do so. Requires rulers with negative traits like buffon or sinner. Wrong faith ruler can work too. Without right dlcs rulers with all stats below 2 will do it too.
This union CB will work on religions diffrent than christianity too since its not "restoring union" but "forcing union" cb wich will generate more aggresive expansion and have prestige penalty but allows you to take over entire country. But you will need to follow same faith to get event trigger still (heretics will have very reduced chance but heathens will never have this)
or:When truce from huge war ends there can be event giving both sides "force union" cb as nobles ask you to take over their king and they promise you loyality if you do so. Requires rulers with negative traits like buffon or sinner. Wrong faith ruler can work too. Without right dlcs rulers with all stats below 2 will do it too.
This union CB will work on religions diffrent than christianity too since its not "restoring union" but "forcing union" cb wich will generate more aggresive expansion and have prestige penalty but allows you to take over entire country. But you will need to follow same faith to get event trigger still (heretics will have very reduced chance but heathens will never have this)