hi xd48
1. What you name 'target folder' is a real folder on your disk, added as a real folder to hfs.
2. When you change in hfs a real folder to virtual folder, then the ACTUAL content (filenames) of the real folder is copied to the virtual file system.
After this:
a) If you add a file to the real folder on your disk, it will only be there, it isn't added to any virtual folder in the filesystem, so it isn't available through hfs!
b) If you add a file to your virtual folder in hfs, it must not be in your original real folder, it can be stored anywhere else.
This means, there exists no 'mapping' of real folders to virtual folders as you seem to have understood. The 'change to virtual' option for real folders, its simply a tool that allows to create a virtual folder with the contents of the real folder in this moment, instead of creating a virtual folder and add then the files manually.
So what you experienced, is the correct way to work. If you want to add a file to the folder in hfs, you ave it to add to your virtual folder!