Interesting...

While it may not be the case here, I remember reading that in some ancient countries/civilizations, the queen was the king's mother rather than his wife. (His wife was a princess instead.)

If a 'princess' had seven sons all who came to conquer and own their own kingdoms, she would become the queen of seven kingdoms...

But looking at how different all these kings look, this probably isn't the situation here. But it seemed worth noting.