This question could pertain to any distro, but I haven't tried a non-Debian-based distro in a long time, so I can't be sure. With every Debian-based distro I've used (Debian, MEPIS, antiX), the installer deletes any existing bootloader on the hard drive, even if it belongs to a distro on another partition. There is no option to prevent this; the installer later asks if I want to install GRUB or LILO, but that's obviously pointless, because I have no choice--the old bootloader has already been deleted, and if I say no to installing a new bootloader, the new distro won't boot. I guess the issue is simple enough: the installer deletes the old system, and the old bootloader is part of it, so it gets deleted too. But what if I don't want the old bootloader to be deleted? What if I'd rather keep it and manually add the new distro to its menu?

All Linux installers that I have used (currently have 13 installs on this box), Debian or RH branch, allow you to say where the boot loader will be installed.

I usually prefer to keep my current boot loader. Have had no trouble with this at all with Debian, LMDE or Ubuntu.

I had no trouble with Fedora or Mageia either.

In the case of Mageia I have to switch back and forth as I am too ignorant to get its grub-legacy to chain load from grub-pc but had no trouble not installing it on the MBR when I installed it.

As this is the Debian section of LQ I assume you use Debian. The boot loader is installed last and I always get a question as to where it should be installed.

If you have it installed on the / partition of a new install it will be fine.

Yipes, I once installed debian without the bootloader (and then the VM would not boot up). The current debian I have has the bootloader installed in the /.
Hope this helps.

Ignore - misread the post.