Given the forum you posted this in, I am assuming you mean LMDE not LXDE.
If you install any Grub2 based os on an existing system where you want Legacy Grub to still control the MBR, do this:
- During install of Grub2 os, LMDE in this case, select option to install grub in root partition NOT mbr;
- when you reboot - go into os you want that still has legacy grub in mbr;
- edit legacy grub's /boot/grub/menu.lst file with something like the following entry
title Linuxmint Debian (LMDE)
root (hd0,4) <----- or wherever your LMDE is installed - use old counting system
This will link to your LMDE partition and will run your Grub2 options from there. You load two grub menus this way but it works fine.
Remember though, issuing "sudo update-grub" only updates Grub2 entries in LMDE; it does not affect MBR legacy grub.
Hope this helps,
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