So I am using only one mod with TTW, this one.
http://www.nexusmods.com/newvegas/mods/36835/?
I used it add all the songs from Mojave Music Radio into Radio New Vegas, because I don't really like that there are songs exclusive to each station. It seemed fine for a while. Then I went back to D.C., and when I got off the train, Radio New Vegas dissappeared (as I expected), so I started listening to GNR and it was fine. But as soon as I stop into the main train station building, GNR goes away, and the Mojave stations come back.
This happens even if I disable the mod in FOMM while my character's save is still in Vegas. However, I tried using the console to go directly from the train (in D.C.) to Megaton, since I thought maybe somehow, because the train station building is not a vanilla building, maybe it's missing some tag or something. That method seems to keep GNR there just fine.
So basically my question is, what exactly happens to the radios when you take the train? Am I right in thinking it simply hides/reveals the proper ones from the list?