Since you cannot merge together countries, the best you can do for now is put the initials of the mega-country to wich the country is part of in the book and adjust the Air and Sea Routes accordingly, based on what the book says, if it doesn't say anything about it just take it as it was supposed be or don't chance anything. Given the scenario, chances are that the best base template is Neurax. Also, since your main target is gonna be the fandom of the book or at very least of its word, don't forget to put references about the book, especially events that mimic what happened in the book, you can put stuff that actually happened there, that was possible to happen but didn't(both explicitly stated and from an headcanon of yours of the community, of course don't forget to explain briefly in any case), or that was pure theory. Adapt the traits based on what were the capabilities(again, but stated and supposed, gotta explain in this case as well, of course) of those who practiced the ideology, then adapt the base stats of what you couldn't implement with traits; for istance there is quite a chance that people don't need a surge of motivation to go on planes to spread the word, so just put Air Transmission as a starter. Finally, don't forget to put a set starter country and a set starter date, they are always cool details to take care of.