I have the following multi-boot setup at present:
/dev/sda: a small SSD containing only GRUB. It has a custom menu with prompts to boot to the OS on either /dev/sdb or /dev/sdc. It's working fine and I can't risk it being changed.
/dev/sdb: a 1TB SSD with Ubuntu 18.04. I need it for work -- it is working fine and I can't risk it being changed either.
/dev/sdc: a 1TB SSD with a previous install of Ubuntu 22.04. Something got broken at one point (no longer relevant) and is no longer booting up.
I need to reinstall Ubuntu 22.04 on /dev/sdc but without risking anything on /dev/sda or /dev/sdb. I'm really hesitant about simply installing 22.04 onto it -- particularly regarding the risk to /dev/sda and the boot loader. In the future I'd like to alternately reformat /dev/sdb and /dev/sdc, putting more advance (fresh) installs on the computer -- but never modifying the boot loader on /dev/sda.
(Note: I also have /dev/sde which is a 2TB HDD used for data shared between the OS's).
