First mi english is very bad, i will try to make simply sentences, i hope you understand:
the names and actions of this groups of people are completely inherent to the RP and the soul of fallout (TTTLA is a exeption) so i think in this:
1.- Factions APK should go to certain map or npc to join into the Wasteland Police (or maybe Lawbringers, or Lawyers if TTLA let that) this dont change the posibilities of join to a faction, NPC or Player-Driven. ONLY FACTION CAN JOIN and every player in this faction will be automatically joined
2.- Same way PK can join to the Psychopat Assasins (or Wasteland Assasins, Mobsters, etc.) same way than APK
And here is the point:
1.- if you are alliated will be a Finger in your inventory, fingers of PK and APK will be diferent:
You see a: Lawbringer Finger
this finger was cercenated from his owner
You see a: Assasin Finger
This finger was cleany cutted from his owner
2.- only members of the other alliance can interact with the Finger. p.e. only PK can see and take the APK fingers, and viceverse
3.- this finger can be traded with certain NPCs for some objects, see the section below
4.- you dont drop a finger if you are killed being weakened
5.- you cant drop a finger to the ground
6.- if you explode the finger will fly too, it use the basic graphic
7.- finger cant be stolen
8.- for prevent abusing of this we only need to be secure of APK arent allied with PK (APK factions are famous, then they are easty to keep an eye on them)
Rewards:
kill in fonline is too "popular" so the rewards will come in great numbers:
1.- maybe like 100fingers can give you a uncraftable weapon: p.e. a Gauss Pistol in change of 100fingers
2.- ammo can be in 2/3 proportions: p.e. 3 "2mm EC" in change of 2fingers
3.- or maybe, like was sugested in other post with the Piramid of rewards, it could be randomly. 50fingers a try
4.- give caps for fingers arent good, there will be too many fingers, this coould jam the economy
Finally as someone says: "only suggestions scripted, with maps and dialogs are added" if we want to make something like this we need to make it, maps and dialogs are easy, but scripts are problem
of course any critic are acepted, even if is aggresive, can help to refine the idea