It is possible to create "new" nations by choosing a nation with similar basic experience and morale and then completely overhauling the Obat. You can edit rank and name text using notepad in order to further change how the nation appears in game. The only thing I haven't see how to do is change the flags as they appear in game, but I suspect this is hard coded somewhere.
Double_Deuce said:
IIRC the flags can be done as well.
Do you know how this is done?
And yes, I think that nations are hard-coded so that if you were looking to add another nation you'd have to sacrifice an existing one. Note that the "Green" and "Red" nations are easy immediate choices.
In theory, Belarus is what you'll get by using the "red" OOB against Poland or Ukraine. The names should fit more or less, and after 1990-91 the equipment will be broadly coherent (maybe add some captured Russian T-64s?).