ubuntu update-grub2 isn't recognising 3rd boot Sabayon

After installing Sabayon, Sabayon took over the boot process. I have reinstalled grub with

sudo grub-install /dev/sda

which I got from ubuntu wiki grub2

Sabayon is an lvm on sda8 and sda9 see below.

sayth@sayth-TravelMate-5740G[~]
[22:03]:fdisj -l
zsh: correct 'fdisj' to 'fdisk' [nyae]? y

Disk /dev/sda: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders, total 976773168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

Disk identifier: 0x104abfd7

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048    27265023    13631488   27  Hidden NTFS WinRE
/dev/sda2        27265024    27469823      102400    7  HPFS/NTFS/exFAT
/dev/sda3        27469824   786911894   379721035+   7  HPFS/NTFS/exFAT
/dev/sda4       786913218   976768064    94927423+   5  Extended
/dev/sda5       786913280   812302335    12694528   83  Linux
/dev/sda6       812304384   816254975     1975296   82  Linux swap / Solaris
/dev/sda7       816257024   871153663    27448320   83  Linux

/dev/sda8       871155712   872179711      512000   83  Linux
/dev/sda9       872181760   976766975    52292608   8e  Linux LVM

However when you update-grub2 it doesn't detect that Sabayon exists, how can I fix this?

Edit I also then tried to redo it using grub-customizer but it just doesn't seem to detect it.

2nd Edit: I think from reading around it doesn't like /dev/sda8 as its a boot partition for the lvm on sda9. It flat out will not recognise it.

Mount the lvm partitions an run the grub update

The most succinct way to enable the volume groups is

sudo vgchange -a y

Simply run update grub to locate the lvms into grub.

sudo update-grub2