Amezona - A Royalty AU

When Amelia Shepherd joins her brother Derek for Princess Callie and Princess Arizona's wedding, she finds more than she'd expected in Arizona, ultimately leading to a romance between the two.
The only issue is that they're both engaged.
How can they get through it?

It's a terrible description, I know. Don't worry, the story's better than this.
I think. I hope. Oh well.