Disable ruing grub when I install a kernel image

Is there a documented, official way to do this, that isn't a hack?

I have a weird setup tetral-boot setup (3 linux, one windows), and I've found that it's entirely hopeless to get the linux image packages to not completely destroy the boot setup; in fact for some reason the linux image updates end up making the system unbootable. That's probably because of some obscure thing I'm doing, but whatever.

I have my own script that I can run to recreate the correct boot setup. Problem is, if I forget to run it after upgrading the keel, system doesn't boot. I want to stop the linux image packages from ruing grub so at least the system will be able to boot into the old keel if I forget to run the script.

I looked at the postinst script for the linux image package, and it's some awful Perl code. As best as I can tell, it looks like if I add a line "do_boot_enable=no" to the file /etc/keel-img.conf it will disable ruing grub, but the code is so unfollowable I'm not sure that's actually the case. Plus, it's undocumented, so heaven knows if somebody down the line is going to conveniently remove it because nobody ever doesn't want the linux image to run grub for you.

I will just mention, parentheically, that applying Windows 7 updates never clobbers the boot setup for the other systems, like these Linux packages do. (All bets off for Windows 10, though.)