@SimLibby I take my words back! Seems like children can be heirs, but only when the hero sim dies. I just tested. My brain likes to malfunction and misremember things like that.
But the importing issue is what it is.
And I don't know if anyone else has this, but I also have saving issue. If I hit the normal "Save"-button, the game screams error (error code 16 or something like that), and the only way to save my kingdoms are through "Save As". And that means I have millions of copies of my kingdom and I have manually delete the spares from my Documents folder afterwards. I just played yesterday and I hit the normal Save button and it didn't tell me the error, so I thought it was fine, but today as I opened the game in order to continue, it hadn't saved a thing. Luckily I hadn't played more than a couple of hours, but still.