From a Logical standpoint, Ludwig is the rightful heir, since he IS the first born and the oldest, yes I still believe the Koopalings are Bowser's kids.
Here's my back up argument, Miyamoto designed them to be his minions from the get go, I guess we Americans and stuff changed it and when they FINALLY saw Miyamoto confirm it and it reached America, everyone flipped
Put Lemmy as the heir of the throne!
Anywho, when will they stop fighting? >.>