I'm probably not the first one to see this

they were all derived from the same empire

*puts the vertical bit in the middle because creativity*

If they included Scania, then they could've included a whole lot more flags...

Nordic Cross

Ladonia’s flag is also a Nordic cross, but both the background colour and the cross colour are the same shade of green. So it looks like a green rectangle

Damn, I guess Denmark is the smart kid in class... (I'm pretty sure if I remember correctly, the Danish flag was the first of all of these to be designed, and is regarded as potentially the oldest continually used flag in the world.)

Christ is king