It's been a topic of discussion for a while now, so here is the straight info:
Belle can't become a Queen because her husband is the Sovereign Prince of a Principality, NOT of a Kingdom. Much like Prince Albert of Monaco.
Same goes for Prince Eric; he is the Sovereign Prince of his Principality.
Aurora will become Reigning Queen upon the death of King Stephan, and co-Sovereign upon the death of King Hubert. If King Hubert dies before King Stephan, then she becomes Queen Consort to King Phillip first, and co-Sovereign after her father's death. Aurora's and Phillip's firstborn will inherit the thrones of both Kingdoms, at which time, Aurora may abdicate and become Queen Mother to the new King or Queen. If Phillip were to die, she would become a…Read more >