Yes I wish to rewrite Relias to play the scenario.
No mods yet, I want to beat the game without mods for 1 play through, then I'm gonna mod it like crazy. But I guess this counts as a mod .
So what you are saying is:
1. Create a sovereign for altar in-game
2. Open up that sovereign's .xml file and change the InternalName field to "Sovereign_Relias"
And I'm finished? No need to swap a file or replace one?