grub or lilo? I'd like to keep lilo but

So, to make a long story short, I was running Debian 9, decided to upgrade to '11'. Left 9 installed on sdc, used the installer to sdb which I had already partitioned as I prefer. But the installer refused to use my existing partitions so I just defaulted back to an install on the drive as one big partition (if that's what you call it when the drive is not partitioned). Got it all running fine. Using GRUB naturally. Then I partitioned sda as I prefer and manually copied all data from sdb to where it would now belong. Ah! but how to boot directly to sda from BIOS? GRUB was installed on sdb. So, since, sadly, LILO seems to no longer be installable, I stole it from sdc (Debian 9) -- just copied it to /sbin on sda -- ran this: "lilo -C rescue" with 'rescue' being: large-memory lba32 compact prompt verbose = 1 install = menu timeout = 40 vga = 0x305 boot = /dev/sda menu-title="RESCUE:sda" image = /boot/vmlinuz-5.10.0-18-amd64 initrd = /boot/initrd.img-5.10.0-18-amd64 root = "LABEL=d5-12-Deb11" label = sda:d5-D11 ---------------------------------------------- (How I love LILO, it just works! You Know and you See what it's doing!) ... and it boots sda with no trouble (here I am!). Now ... it all works, I understand it and want to keep it. But LILO is now history, so it seems, and I'm wondering if anyone can recommend a doc that will give me the best info on how to install GRUB on sda entirely manually if that's possible. Research to this point seems to say that you hafta use the install media. There's a thousand hits, Googling for answers, but I want to make sure I have the recommended doc. Or perhaps I just just leave my faithful LILO in charge? I know! -- folks can't stand things that Just Work, life is not meant to be simple. Like the government, GRUB and SystemD know what we need better than we do. Top