Choose Your Religion

For example, you can allow yourself to be captured and then, after a couple of generations, become the ruler of the conquering state.

I'm already part of Scotland. But I don't think I'm an heir, just a relative of the monarch: there's a claim to the throne, but the chance of becoming monarch without forceful intervention is zero. Or maybe some intrigues, although I don't really know this mechanism yet. Perhaps that's another option.