I'm the King of Norway and England in house Yngling. I may soon be able to create the Empire of Scandinavia. Ewan, the King of Scotland, is in house Dunkeld. Ewan's only son and heir is Ale, my grandson, who belongs to house Yngling through a matrilineal marriage.
Scenario 1: Ewan dies in a mysterious hunting accident. Ale takes the throne of Scotland, and he's a member of my house. But he's a king and I'm a king, so he can't be my vassal yet. Then later I form the Empire of Scandinavia. Does Ale become my vassal when I become emperor?
Scenario 2: Ewan stays healthy as I finish cobbling together the empire. Now I'm Emperor of Scandinavia, and then Ewan tumbles from the parapet. Does his heir Ale, as a member of my house, become my vassal when he becomes king of Scotland?
Scenario 1: Ewan dies in a mysterious hunting accident. Ale takes the throne of Scotland, and he's a member of my house. But he's a king and I'm a king, so he can't be my vassal yet. Then later I form the Empire of Scandinavia. Does Ale become my vassal when I become emperor?
Scenario 2: Ewan stays healthy as I finish cobbling together the empire. Now I'm Emperor of Scandinavia, and then Ewan tumbles from the parapet. Does his heir Ale, as a member of my house, become my vassal when he becomes king of Scotland?