I've been thinking a lot about the ways I'd like to handle the various mechanical changes I'll need to make in order to bring Birthright forward, and I've gotten several avenues of feedback about my intended methods. I'm not so stubborn as to not let discussion change my mind, as that is a death sentence in game design.
So the following are points of contention that I am flopping around about, and will decide for 100% certain when I get to the respective articles.
Races and Blooded Scions
Caiomhe probably hit on something good with the decisions made for the races. Harbinger
So I'm going to mea culpa there and concede that the choice to be a blooded scion is one made at first level, through selection of variant racial packages. I don't think I will do quite the same arrangement as aforementioned PDF conversion, but the general idea will be similar. Also, the stat bonuses might be troublesome, because...
Nix Honor, Add Bloodline
Hero With a Thousand Hit Points had a great suggestion in using Bloodline as a new, Cerilia-specific ability score for players who are blooded scions. And in thinking about it for much of the day, I'm liking the idea more and more. Hear me out.
As the DMG suggests, adding a new ability score (from their examples of Honor and Sanity) gives you another score to roll for, more points to add in point-buy, or another 11 to place with the standard attribute array (full disclosure: I prefer the standard array for a lot of reasons that would take a whole blog entry to cover). If an ability score is used, you can increase it via level-gains any time you would otherwise increase an ability score, it creates a notable (and likely difficult) decision on character creation on where to place your best scores, and gives humans (who are typically possess the most potent bloodlines in the setting, short of awnsheghlien) a slight advantage in where to place their bonus ability points.
This also helps give the player more control and less blind randomness in how strong their initial bloodline ends up, and neatly delineates the different bloodline dilutions. To wit:
1-8: TaintedHarbinger expressed that this didn't feel right, and I feel like I am getting the same itchy sensation about it, but it helps tie a great many future features together. Regency Point gain based on ability modifier and proficiency bonus. Blood abilities that scale based on how strong you make your ability score. Heck, domain action resolution can use a Bloodline ability check to resolve actions that don't already reference another skill proficiency.
So this is what I'll likely be shifting toward as we continue on this blundering design journey of mine. No promises I won't be convinced otherwise later on, though!