There is much more to a group showing up from the particular campaign MIS file they are in. Most of those files are "loaded" with the Campaign.cfg (Fleet Boat side) or CampaignGE.cfg (German side) files, so that also determines when a particular group would show. The folder structure on the German side is also different from the Fleet Boat side. I wouldn't "merge" anything, except maybe the Campaign.cfg file with the CampaignGE.cfg file, but keep it CampaignGE.cfg in the same location. Be sure and make a copy of the original GampaignGE.cfg file before you begin the process. The game can and will reach across the folder structures, as can be seen by a few of the calls in the CampaignGE.cfg file. One thing to keep in mind here, is that you would be in essence, doubling some of the layers, which would mean much more traffic than anywhere near historical or even the overblown SH4 Stock proportions, if you keep both sets of files. Therefore, you won't need some of the layers. It can be fun to experiment with this stuff, but it can also be very frustrating...
- Big thing - you'll find that the US and Australian traffic levels and patterns are not based on anything except what someone plugged into the game. Nothing like RSRDC. Lurker might have some in the Operation Monsun mod, which if he does, would be a much easier undertaking than what you're trying to do...