I occasionally enter the Disney wikia to see entries on this series and its main characters and I've found these names:
Sofia Amanda Milledtion
Amber Santa Barbara McArthur - Lady Santa Barbara - The Other Queen Victoria
Prince James D'Artagnan Milledtion - Lord McArthur
Miranada Leslie Balthazar McArthur
Yes, I know it's written "Miranada" instead of "Miranda" but that's not the point. Where were these surnames found? Why would Amber be known as "The Other Queen Victoria"? Why would James use the surname "Milledtion" while his sister and his stepsister use "McArthur"? Why would the title of Lord McArthur go to the only royal sibling (according to that wikia) not to use that surname? I'd be glad if anyone had answers.