Although Link Shell Extension works, linking a folder to another folder (or drive) it is just another thing to try to set up and maintain. Here are two ORBX posts: the context and Nick's post on how to do it.. (This is concerning concerning ORBX scenery but it applies to any). In reality this method simply "fakes" the orbx and windows registry entries to read the location of the moved content.
The orbx posts:
The context:https://orbxsystems.com/forum/topic/186967-how-to-move-fsxorbx-folder-to-folder-outside-of-fsx-folder/?tab=comments#comment-1619678The how to: https://orbxsystems.com/forum/topic/146877-using-a-symbolic-link-to-move-the-orbx-folder/
The Link Shell Extension program: https://schinagl.priv.at/nt/hardlinkshellext/hardlinkshellext.html (Freeware).
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BUT - if you are just moving P3Dv4x scenery or you want to move other pieces over to an alternate location, you don't really need to use hardlinks to do this..
If you were moving programs, it would be better (and cleaner) to just reinstall the original programs, (save the data first): reinstall the programs on the other drive and reinsert the data (and your windows registry will be up to date and exactly correct without the use of symbolic or hardlinks).
Now if you're simply moving add-on sim scenery folders/files or other folders from your P3Dv4x over to another drive you can do it in a flash (just cut/paste it over) then with the use of the scenery.cfg for scenery locations just change the path and your done. (Or edit the paths in the addon.xml if you use that method)
You can also move add-on simobjects, effects, gauges, fonts, sound, etc etc etc and add the paths to your P3Dv4x configs files IE: simobjects (Most of them work outside the sim folder), also can move addon effects, fonts, gauges, etc etc off your C:\ and move them all over to another drive and edit theire config files. (These config files are all located in your C:\ProgramData\Lockheed Martin\Prepar3D v4 folder.)
(Or reinstall your sim over to your other drive and have all your sim over there. (there is an easy way to save most everything in your new sim location). "Lots of ways to skin this cat"
If you need a hand to do this - can give you a hand via teamviewer. Wouldn't take long to do at all and moving stuff off your C:\ drive will save you that critical space required for that OS drive.
Norm