But croatians didn't have the least word to say about that, especially later at the time of the Dual Monarchy.King of Croatia said:Not really,since we had the same kings,but we were two kingdoms,same thing with the Habsburgs,all those kings had to be crowned kings of Croatia in order to rule it.
BTW, I don't think historical monarchs, as they're mostly Habsburg (and those that aren't are hungarians or poles). Since Croatia in independent in Aberration, we have to find new monarchs.
Do you know some line of proeminent croatian nobles that could have chosen as kings ?
Same thing with events, we need a few fantasy events.
The best is that you play a game of Aberration (with Croatia or another country, Eire is interesting, and Bavaria is fun), and see the global setup. This'll give you ideas.