How to add new nations to winSPMBT. There are empty OOBs and existing nations to chance with Mobhack, but....
-How I can chance
1.Flag
2.Nation Name
3.National values like
-a. Base Experience
-b. Base Morale
-c. Hidden artillery spotting ratings
The "For R&D Only" OOBs are just that. There is no space for new nations in the game, and the design team is not looking to change this and add new nations any time in the near future.
The only option available now is to find an OOB with a relatively close set of national values and dates of existence and create your own OOB in its place (and then create flag icons and such to make it easily recognizable). Note that this is not as easy as it sounds, but by all means if you have a country you want to see go ahead and put the effort in. If nothing else you'll have a great personal sense of accomplishment.
What OOB are you looking to build? I'm curious now.