Relative path for VFS (Virtual File System)

How do I set relative path for the VFS? The UI in rpcs3 does not allow me to and editing config.yml doesn't appear to work either. In fact I found explicit code in rpcs3 that "fixes" my manual modifications of the path (https://github.com/RPCS3/rpcs3/pull/5523/files)

Scenario: rpcs3 and the games are on an external drive, but in separate folder structure:

>Launchbox/Emulators/rpcs3
>Roms/PS3/dev_hdd0

I need to provide relative path like so: "..\..\..\Roms\PS3\dev_hdd0"

Thanks!