All Factions From All Campaigns In One Menu For Custom/Multiplayer Battles

[Tietonian]

My dream mod at the moment is to have all factions from all campaign DLC in the Grand Campaign battle faction menu. I would, for example, want to play the Belgae (CiG) against the Ionian League (WoS), or the Etruscan League (HatG) against Octavian's Rome (IA), &c.

Is this possible? If so, how should I get started? It would be nice if someone could point me to a detailed guide which explains how to make a single, non-DLC, faction battle-ready. I understand there are several "All Factions Playable" mods, but I would like to know how it was done.

Thanks.

[Demokritos]

Edit:

It used to be a simple affair to add a given faction to the factions lineup in custom battles. For ETW, for example, all you had to do was to open the DB file called "factions" (located in some "data.pack" or other in the game's data folder) with the Pack File Manager (PFM) and then tick the columns for "early_availability" and "late_availability" for the faction in question in that file. Something similar had to be done for later games. For R2, at least, you also had to edit another DB file ("units_custom_battle_permissions") in order to make units for the given faction appear selectable for the custom battles. With the last official update or patch for this game, however, the simple solution for said end no longer seems to work or suffice.

For R2, if you wish to play a given faction of the game against any other in custom battles, you also need to find the file which determines under which scenario menu for custom battles a given faction appears and then see to that they all appear under the same scenario (e.g. Grand Campaign etc). Such a change may create a practical problem, however: so many factions listed on screen that you cannot see them all in the window and no means to scroll beyond. So even if you find that file, you may have to limit the number of factions selectable for custom battles.

If anybody has found the answers to these questions, please share them with the community here.

Edit 2 PS. Found a DB file that may, just may be the one telling the game engine under which campaign heading a given faction is to made available for custom battles: "campaign_mp_coop_groups_to_factions". But, after that last patch, there still seems to be something missing for a new faction to appear in the menu for custom battles. All "faction unlockers" out there appear to have ceased to work...

Edit 3: Thanks to Dresden, I discovered another file relevant for this undertaking: "faction_to_campaign_junctions". If also editing this file, new factions do appear in the menu for custom battles. BUT...now it seems the number of factions you can add in this is capped. I've only managed to add 2 so far...

Edit 4: Discovered what the problem was and can now confirm that all you probably need to do is to edit the DB tables for factions, faction_to_campaign_junctions and units_custom_battle_permissions in order to get new factions to show up on the menu for custom battles. I've not tested to put a faction in a campaign where it does not belong originally, but it ought to work, so long as there's space left on the faction list to fit inside the window.

Spoiler Alert, click show to read: 

Edit 5: I can now also confirm, as suspected, that the enablement of many more factions for play in custom battles creates a problem when it comes to selecting a given faction from the faction list. For the normal grand campaign alone, only the 3rd and 4th faction as defenders get to see the whole faction list, as it extends downwards only a little and leftwards from the pull-down-list button; the 1st faction as attackers can only select from Knossos and later in the alphabetic order, all other factions as attackers have an even more limited selection. So if all factions in the game, some 550+, are enabled for a given campaign, it's literally practically impossible to get any two of them selected for a custom battle: many of the factions in the beginning of the alphabetic order will simply be out of reach.

Edit 6: Might as well illustrate the aforementioned problem and at the same time prove that it's possible to put any faction in the game into a given campaign heading, as Prologue factions show up in the Grand Campaign selection below (the former listed first, "Rome" here standing for Roman Allies):

Spoiler Alert, click show to read: 

Edit 7: I've released a small factions unlocker here. Only one campaign is fully unlocked so far, faction-wise (not unit-wise), but you can use it to expand its function to your own liking.

[Rafter_Man]

bump. I want to use Grand Campaign units against Empire Divided units, etcetera