I don't like the "stanza" you added to hda10../boot/grub/grub.conf . You should IMO have used a stanza like this:
This causes the hda8 config file to (when selected) pull up the hda10 config file. Thenyou need don't need to manually edit on kernel upgrade.
If you boot FC7, and you type "grub-install --no-floppy /dev/sda" then the this re-writes the MBR to boot the contents of the current /boot/grub (which is on sda10).