Slitherine

I was wondering if there is a way to add more nations to the core in the "vanilla" blitzkrieg campaign..other than the freebie units

IE: Italian, Waffen SS, etc....

Personally I think it would be cool to be able to buy an allied unit and it keep in my core

Thx in advance for any help

edit: I tried editing the data.cmp file, but the "new units" weren't showing up as purchasable core units