I have done a quick test in virt-manager:
Create a 40G virtual disk
Install Fedora server1 using ext4, 10GiB as vda1, reboot.
Install Fedora server2 using ext4, 10GiB as vda2, reboot.
Install Fedora server3 using ext4, 10GiB as vda3, reboot.
After the 3rd installation, grub2 is using /dev/vda3/boot as the configuration.
The entry for server2 and server1 is discovered by os-prober, so they will list below server3 by default.
I can manually edit grub.cfg to adjust the menu orders. But I can see there will be issues:
- once I do a kernel update, say, in server2, it will run grub2-mkconfig automatically. It should make /dev/vda2/boot as the active configuration source for grub2.
To more consistent / easily managed grub2 booting, personally, I will do:
sda1 - boot shared for all installations
sda2 - server1 rootfs, mount sda1 as /boot and sda5 as /home
sda3 - server2 rootfs, mount sda1 as /boot and sda5 as /home
sda4 - server3 rootfs, mount sda1 as /boot and sda5 as /home
sda5 - home shared for all installations