In my current campaign as Skaven (Clan Mors) I control most of the map. All other Skaven clans were either wiped out or merged into my rat-empire through confederation.
There is however still Clan Skryre and since I don't own the DLC required to play as them I'm currently not able to propose a confederation.
I don't want to kill my rat-bretheren but I'd also really like full control of the continent they're currently at so the easiest way to achieve this would be through merging them into my own faction. Also taking control of them would give me some helpful troops (DLC units) and their leader.
My question now is:
Will the option to propose a confederation show up in my existing save file if I buy the DLC or would i have to start a new campaign to see that option.
I'm also interested how this works with DLCs from Warhammer: Total War I since for the Mortal Empires campaign some factions are only unlocked through the respetive DLC from the first game.