Then with Distros 2 to x, point them in the install process to use Distro 1's Home as their home (but do not reformat or you will lose data generated in Distro
Is it obvious how to do this from the installer or is this something that needs to be done on the CLI?
Does Manjaro require a separate /boot/efi partition for each drive if there is a ssd and an hdd?
Funny how that happened!?!? I like the new picture by the way!(& G'day again . Fancy meeting you here)
However the first time it runs is before we get to the choice of manual partitioning, erasing the disk and installing, installing alongside your current OS/OSes &c. So as part of that, Linux already knows where (in a UEFI-GPT environment) your ESP is, that is, /boot/efi .
Did you pull back from the install of Xfce or pursue it to completion?
If Linux cannot find an ESP, it will prompt you to specify one.
I get an error message that I did not designate a boot partition and the system may not boot properly.
blkid #might need a sudo in MJRO
BTW if your MATE is up-to-date it will now be a v18 codenamed 'Illyria'. Manjaro works on a Rolling Release model cf a Point Release model such as Ubuntu and Mint &c.