this can help?...
FreeBSD boot partitions are 2, 5, 8. I created the following
"/etc/grub.d/10_freebsd" file, so "update-grub" does not remove
FreeBSD from the boot menu.
#!/bin/sh -e
cat << EOF
menuentry "FreeBSD 7-STABLE AMD64" {
set root=(hd0,5)
freebsd /boot/loader
}...