Ubuntu: how to prevent grub installation

I have several linux installations in my system, and I like to control the only boot partition from my main linux distro.

Sometimes I need to update the kernel image in my secondary linux distros, but apt tries to install grub. I don't want that. I often had to let it be installed and remove it via apt remove.

A better, permanent solution is to add this file preferences.

Thanks to: jdthood answer in stackoverflow.