I have my own grub partition sda1 and various distros in sda2-7 (GPT). My grub installation on sda1 has a manually crafted config, background images etc.
Recently I installed another distro and it installed it's own grub in it's own partition sda7. It detected other distros mostly correct but I want to use my own grub from sda1 because one day I will delete this distro and still want my own grub working. What exactly I have to do now?
I am lost because there are dozens grub-TAB programs and grub-install has multpiple confusing options like devices directories images etc.
I know there are BIOS and UEFI installs but this is so confusing I do not even know which one my system has now. I remember creating 100MB fat16 disk for uefi but if any of the distros used it is unknown.
Can I simply type
grub-install /dev/sda -d /mnt/mygrub ?
sda1 ext2 grub
sda2 efi parition I created manually empty, not it as some files created by ubuntu install
sda3 btrfs linux from scratch
sda4 btrfs debian
sda5 btrfs freebsd
sda6 ntfs reactos
sda7 btrfs ubuntu
I have sda1/boot/grub/grub.cfg with all the menu entries.
Now sda2/EFI/BOOT have something else that I cannot really recognize. It has grub.cfg also.