First of all, welcome to modding. Small projects like this are what got me hip deep into making my own version of FE.

Secondly, I have a few clarifying questions:

1) Did you edit the CoreUnits.xml file in the base game directory or put yours in the mods directory. Try backing up the original file and replacing it with your edited version in the main game directory. The mods folder is poorly implemented and many things do not translate from there correctly into the actual game. Obviously you ALSO have to back up your modded file, because a patch will obliterate it.

2) Look in the CoreUnits.xml for heroes with no allegiance. These heroes will have tie ins to quests (as opponents) or quests (as recruits). You should be able to compare these sections of the xml to normal heroes to see what you need to do to make a hero have no allegiance to one side or the other. If none of this works, you could always cut and paste the sections of an existing quest to do nothing but offer an unaligned hero.

I do not believe any of this is possible, unfortunately. Keep trying though!

None are both allegiance. Special can be either empire or kingdom.

Is there a special shortcut you need to start the game using edited xml? That might mess up ins2's efforts if missed.

Heavenfall I have another question

In your A_LIB_UnitStat_BG_vZG you have a folder called "CoreReplacementFiles" which has versions of CoreUnits, CoreWeapons, CoreSpells and CoreArmor

This is a problem for me as they override any changes I make to my own Core... files (located in my games directory), and I am having trouble making any changes to your files because they seem to have lost their formatting (no line breaks) which makes it very frustrating to try and change them

What exactly is it that you've changed in these files?

Remember that I am only using the reliquary to add your wonderful items in my own game.

Would it be possible to delete these files without severe repercussions or bugs to the reliquary?

Just to avoid any misunderstanding, I want to make some changes to my own CoreUnits, CoreWeapons and CoreItems file ONLY FOR MY OWN GAME...

Many thanks for your patience and help on this,

Best regards, Bendiwolf

I think there might be a way to circumvent the problem with heroes being Empire or Kingdom: quest heroes. If I am not mistaken, quests can be taken by either faction, and the heroes that you get through them can work both ways. So, you'd only have to create the hero as a unit and put him inside some quest... It might work,