Combining multiple drives containing same folder names to a single folder

[zahroc]

Trying to determine the best setup to accomplish what I will describe, hopefully clearly.
On my gaming machine, I have STEAM installing games to different drives, H and S. The drives have the same folder structure but contain different data/games due to drive size limitations.

I am trying to combine them into a single drive for backup purposes, i.e. Z:, using FreeFileSync. This is something I would like to eventually setup on RealSync to keep it up to date for game updates, saved games, etc.

Suggestions?
TIA

[xCSxXenon]

There is an "update" option in FFS that will backup new/existing files, but won't delete them from the destination even if they don't exist in the source