A new alicorn for a new world? Good idea or lore breaker?

I have been coming up with a new idea for some time now and I would like some advice on it. I've been working on creating a new fantasy universe or world that goes together with the main series. Equestria is just one nation among many is a big world so naturally there are other places in the world that are not featured and left to the imagination. This world I am creating is essentially going to be the setting for the stories I am hopefully going to write. To give a very brief description, it goes out like this:

The stories are going to be set on the distant continent of "Hippora", it is kinda like the MLP equivalent of Europe, but has a more Eastern European vibe to it. Imagine the Baltic Region being the size of a continent. On this continent there are of course nations, kingdoms, etc. One of those nations is the "Principality of Arinthia" and it is the sister kingdom/military buffer state of Equestria. The Principality is lead by an alicorn prince, who I envision to be the cousin of Celestia and Luna.

I am currently working on the Bibles for this world within the world of MLP, that will go into detail about the world and characters. But what I wanted to ask the community is if having the Principality lead by Celestia's and Luna's cousin is a good idea. The alternative is having the Principality ruled by a form of constitutional monarchy with several royal families. As far as I know, the royal family tree of Celestia and Luna is virtually unknown with the exception of Prince Blue Blood. Does having an alicorn rule over the Principality add one too many alicorns into the universe and can possibly be lore breaking in someway?