How to edit grub menu list?

[drsmk]

Hi, i have dual booted my system( vista with ubuntu). Now i want to triboot by installing redhat. Whenever i try to install redhat it overwrites the grub and im not able to boot into ubuntu and vista. I have to restore grub in order to boot into vista and ubuntu.
Now i wil again install redhat but wil not install bootloader this time. My question is how do i configure (ubuntu)grub menu list
So that i can triboot. suppose i make redhat boot partition in sda8 and root partition to sda9. How to map it into (ubuntu) grab menu list.

[pmlxuser]

after you install the redhat do a grub reinstall using ubuntu disk everything should be fine.

[drsmk]

you mean that i install redhat without installing bootloader to mbr and then reinstall grub using ubuntu.