Thanks a lot for your suggestions!!!
Hi to all!
Just to know if there is anybody around still working on this topic!

I'm trying to figure out how to integrate into the Birthright campaign setting two aspects of FC rules:
1) The Reputation points system compared to that of Regency Points. I'm inclined toward considering the Reputation Point the "non-noble" version of the Regency. This basically means that:
- You cannot use reputation instead of Regency : A blooded scion is still the boss.
- You CAN use Regency as reputation to obtain the listed favour.
How to handle technically this mechanics is what I'm looking help/suggestions/ideas about.
I kept these 2 completely separate. Everyone has reputation. Blooded regents have Reputation and Regency Points.
When I was working on this, it ended up that there really wasn't any overlap between the functionality of Regency and Reputation.
Ok, you convinced me on this. One less conversion problem!
2) The Panache/Prudance application to the Domain. I think it is nice to have a regent that burns money compared to one that is more parsimonious. This lead also to the question: is the domain turn a long downtime?
I didn't change the way money was handled on the domain level. I set the value of a Gold Bar at 1,000s and applied the Prudence value to it when converting Gold Bars to Coin in Hand. Cashing in a Gold Bar would only net 150s for a Prudence 0 regent. Further, that put the money into is Coin on Hand. Converting it to his personal stake would require another Prudence hit.
In practice, my group would tend to commission some item, then cash out Gold Bars as needed to pay the guy.
There is a domain action called something like "Ply Trade". This action basically gave the character a 1 month block of downtime. Non-regents could also take this action. If you took any other action, you were basically too busy with affairs of state to warrant taking downtime.
Again, I love your solution!
I have other problem, like integrating the two holding management systems or the Renown... but the listed two are the most important for now!
Thanks a lot!!!
Much like Reputation and Regency, I kept these two completely separate. Birthright "holdings" don't refer so much to actual ownership of physical places as much as your influence and control of political entities. Fantasy Craft Holdings are personal prizes for your character.
All of the holdings normally associated with Birthright are tied specifically to that system and give you the benefits listed in birthright. If you want to gain benefits from the FC system, you would have to spend reputation to purchase the holding as normal.
I treated these as distinct entities. Losing one had little effect on the other. For example, if another regent succeeded in contesting your temple holdings in a province, you would not lose your FC holding that happened to be a temple. Another regent may have managed to change the predominant religion in your province and you are losing a lot of Gold Bars that were generated from those holdings every domain turn; however, your personal temple is still yours to run as you please, though the congregation may be reduced.
On this... Your solution works, in fact... And I could adopt it initially, but I will continue to work on this. I think it can be nice to have players upgrading some aspects of their holdings using reputation. Or, said in other words: that they upgrading of their holdings using Reputation have some reflect in the Birthright system.
Renown I just continued to use "as is". Higher renown continues to open up prize slots and favours and is raised with reputation as normal.
Instead I'm thinking to something like this: the personal Renown remain as it is in the FC rules but regents can use their highest owned holding level instead of renown for relational / favours bonuses only. About favours: if you can access a given favour only thanks to the holding level (and not because of your renown), you have to invest more Reputation on it.
Moreover: the strength of your blood may and should influence your renown (at least for the relational bonus, but also, maybe, for some family magical heirlooms).
I would like to add one more renown "path": the clerical one. Basically similar to the noble one, but within your church. Still not sure about this.
One last thing: can your legend score be added to your collected RP? Directly as a bonus or as a value to be added to your blood score? (I use the classic 2nd edition system for blood)
Thanks again!!