How to make GRUB set the root device as the EFI booted device?

**XY problem:** I have multiple Debian Live OSes (made through live-build) on multiple drives in my system, but whichever drive is booted to it just loads the squashFS from the first drive. It looks like the boot=live parameter is looking for the files in the /live directory (which contains filesystem.squashfs), however it appears that GRUB is just getting this folder from the root device (which is seemingly static depending on how the BIOS sees the drives) and not the device which is chosen to be booted from*. **Is there a way to make GRUB set the root device as the drive which the EFI booted to?** Or is there another scalable/non-hardcoded way to load the desired squashFS? *It's also a bit odd because when the live OS is 'burnt' to the drive there is no option in the EFI to boot to the drive, yet it is still bootable 🤔