Just boot into either linux distro and re-run the liloconfig utility. You can add your newly created partition as a boot option form there.
I have a machine running win98 on hda and mandrake 9.1 on hdb. Lilo is the bootloader for both os. This works fine. I got curious and created another linux partition on hdb and installed knoppix 3.2 and created a boot disk to load it. Everything works (much to my suprise!) I was fearful of corrupting my nicely running machine by changing lilo. How can I edit lilo to safely load all 3 os?
Just boot into either linux distro and re-run the liloconfig utility. You can add your newly created partition as a boot option form there.

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