You can try Link Shell Extension
(the link is supposed to be for the 32-bit app, the 64-bit exists as well, just make sure you get the right one). Basically what can do for you, it can create links or junctions pointing to the actual files. So, if you put your links in the same folder, Windows will be "tricked" into thinking that your files are actually there. This definitely works for Windows. Maybe it will work for your backup software as well.
The website provides extensible help, but the following instructions basically taken from the SSD tutorial
may work as well: Create a target folder.
Navigate back to where your file is actually stored, right click and select Pick Link Source.
Navigate to your target folder and select Drop As and select Junction (actually this was in instructions for linking folders; for your files you may need to try other options).
Now, in your target folder you will see your file again with a little overlay icon.
Repeat for all other parts of your archive.