GhostKing!Maddie
Reveal gone right. Good parents Jack and Maddie.
Danny tells his parents that he’s Phantom and they accept him with open arms and hearts and the willingness to change their views. With this they start their research on Ghost culture, because that’s a part of their baby’s life (afterlife?) now so of course they’re going to make sure they understand their son so as to avoid potential culture clashes in the future.
(Did you know ghosts fight as a form of bonding?! Fascinating!)
At some point in their research they learn that the method of succession for the title of King of the Infinite Realms if for the former king to be defeated in trial by combat.
They learn that Danny defeated the former king tyrant Pariah Dark.
Their little Dann-o is the new King.