What *is* a Sovereign Princess?
Only problem is, I can't figure out what a sovereign princess is. I've read up on the ruling family of Monaco, but nothing has explained what the title means (and Sovereign Princess there seems to be a tradition thing?). I have friends who know more about royalty than I do who've said it could be like a princess consort who succeeds after the King's death, but aren't sure.
If it helps, my story is set around 1250 - 1300 in fantasy Germany-- not to specific because I'm trying to keep it in fairy tale-ese, and Tchaikovsky wasn't exactly specific to begin with.
Bonus question: what on earth is the term of address for a Sovereign Princess? Just "Your Highness"? I've seen in Monaco it's "Serene Highness" but that could be for when/if Caroline becomes Sovereign Princess and not a long-standing title?
I've gotten a lot of hits about horses, alpaca wool, and Swan Lake has shown up a few times. I can easily change her to a regent, but I really like the sound of "Sovereign Princess," so I'd like to use it if it suits my purposes.
Searched: "sovereign princess," "what is a sovereign princess," "sovereign princess" + royalty, and other permutations. Google Scholar isn't very helpful either.