I hope for your sake that there are not problems if you intermarry with Swedish pagans. In CK1, I once had a game as Kingdom of Leon where I married into my Muslim vassals' families. On the bright side, I actually had my grandson inherit two Emirates, one in Spain, one in Arabia, but on the downside he died a young man and his young Muslim son (Sayid Jimenez, i think he was called) and so suddenly game over.

But a game file edit later and we were back in business
The point is that the religious divide can be a bit too heavy. I do hope that pagan and Muslim succession laws are enacted for those realms to make their successions realistic, maybe Turkish Succession for most Muslims and semisalic for Berbers (for whom the eldest grandson inherited, if the titleholder's oldest child was female) and primogeniture or gavelkind for pagans.