OK, so I know I'm not the only person with this theory, but I think it makes sense either way. What if Princess Genevieve from Barbie and the 12 dancing Princesses is Queen Genevieve from barbie as the Princess and the pauper? It makes sense. Anneliese looks exactly like Genevieve(although they are both technically played by Barbie so that could be irrelevant)

We only see Anneliese's father during one of the stills shown during the opening narration. And we never learn his name.

So here's the family tree I have in my mind currently:

King Randolf and Queen Isabella

Genevieve and her sisters(Ashlyn being the eldest) and Derek

Anneliese and Julian

Liana and Jeremy(from Diamond Castle)

Eden's mother(as well as her aunt Marie)

Eden Starling

Their great-grandchildren

Barbie and her siblings

ERIKA'S SIDE

Erika's parents

Erika and King Dominick

Alexa and Ian (from Diamond castle)

Kathrine's parents

Kathrine beadnell

Their great-grandchildren

Theresa and her family

And anything in the realms of the Fairytopia Trilogy/Mariposa film would be happening simultaneously with the Princess and the Pauper, so that's a separate timeline. 

I also think maybe Preminger could be the son of Rowena and Desmond. Preminger and Rowena both want to be ruler, they look somewhat alike(at least I think so), they have similar personalities.

Let me know what you think :)