but if I'm understanding correctly I would then be able to say merge saves from different devices into one "bak" file, as long as the games I want to merge occupy different slots.
Well, I'm not exactly sure what you want to achieve and why.
But, what you can do is have something like "data bank" of saved games (i.e. save slots) from different devices and you can exchange them between devices, by manual manipulation of save slot content.
You can take save slot 1 from device A, put it in save slot 1 on device B (keeping other save slots intact) and also, before you do that, you can save slot 1 that was originally on device B, thus saving it for future use.
Or, to say it a bit differently, now you can have 10 save slots, i.e. ten games (characters, of whatever you'd call it). But, with this save file manipulation you can have as many as you want, keep them in some place on your HDD (or SSD
) and exchange it as needed.
So, you can keep and play more than 10 games, actually, with this you can play as many as you want games, only they need to be in certain slots, i.e. you must keep their directory names same forever.