While I made new parent factions in Arnheim, I did not do so in the Llyra/Vives project. Yesterday after leaving the module fallow for months I decided to tinker with it and ran across faction bugs.
Background:
I use the core parent factions for people NPCs. Commoners, Defenders, Merchants. And I added a new one as a child of Defender called Leader.
For animals I created four factions, and they derived from Commoner and Hostile depending.
Situation:
In Nocthairy forest I set up a camp of woodsmen that NPCs can interact with. It has "commoner" woodsmen which are the low level mooks around the campfire. There is a "merchant" faction NPC who sells stuff, and a "leader" fction NPC who does not yet have a full conversation so is primarily there for DMs. I also flag all of these NPCs as belonging to their own group - "Nocthairen_Woodsmen" - which I use in my custom AI so that these guys know that they are affiliated with one another.
Since all of these woodsmen have ranged weapons they are a good safe area if you get overwhelmed by a herd of mountain goats, cave slimes, or goblins. Yesterday while testing with a level 1 PC I ran to their camp with a mountain goat chasing me. They killed the mountain goat. Then when the goat died the merchant and the commoners fought each other.
And not only did they kill each other, but the bluejays in the woods went hostile too even though they belong to a different animal faction than the goats. Thankfully bluejays fly away when they are hostile rather than flock to the attack.
Anyway... turns out that the bluejays and mountain goats have factions with "commoner" as a parent.
I have not had time to test my solutions to this problem but here is what I did:
I edited the faction file in the module repute.fac or some such. Its the only file ending in .fac
No custom factions have commoner as a parent faction anymore. I changed all the custom factions to derive from hostile.
Another solution I am thinking of is creating new parent factions. Perhaps all animals should derive from a "neutral" parent faction.