Thanks fellows, for that. One folder, but two start options, although they both take you through the v1.5 SH4.exe file then... So there really should be no confusion as to which folder gets modded... By default, do they still use the "Silent Hunter Wolves of the Pacific" for the folder name? In my experience with the Steam SH3 and SH5, the use of the Steam verification will wipe any MODS from the game, so remove any mods with JSGME, and move your MODS folder to a "safe" hiding place prior to running the verify.
With my Steam SH3, I take that "stock" Steam game folder and make a zip file of its internals for archival purposes, and to use that as a base for my modding. In other words, I move into the "F:\Games \Steam \SteamApps \common \Silent Hunter 3" (or whatever) folder, and zip up its contents into an "SH3archive.7z file (the Data and other folders, as well as the *.act and *.dll and other supporting files - not including the base folder). I then make an "SH3Archive" folder (or some such) and cut and paste that 7zip file into it for "safekeeping". I can then make another new folder for each of my intended mods, and copy and paste that archived 7zip file into each of them, such that with a stock "Steam" game, I will have the "base" folder structure of "F:\Games \Steam \SteamApps \common...", and below that have the stock "Silent Hunter 3", and then a folder named "GWX" for the Grey Wolves mod, "LSH2015" for Living Silent Hunter, etc. Unzipping the archive then gives me an un-modded copy of the game. Bring in all that is necessary for the mods into the copied game folder, and after setting it all up, I will then use the Steam App on my computer and "Add a non-Steam game" to the Library, then re-name it to reflect the mod I'm using (as seen in the post pic above), and start it through the Steam menu, and presto-bingo, I can play the modded Steam versions, and have my Stock version too.
I do not know (of course) if that would work for SH4, but I do know it fails for SH5. Using TWoS on it, it will mod the Stock folder... but I still made a 7zip archive of the folder internals prior to modding, though I have not had occasion to use it, and hopefully won't...
