Interesting idea! Hmm. I'm thinking - drop one unit of Morghast, drop the 10x Chainrasps unit, remove 5x Revenants from the 15x unit. This means I can keep one Morghast unit, while also adding a 20x Reaper unit.
So keeping one Morghast unit of 2 because they seem pretty damn good (I don't know, I feel hellbent on playing one atleast once), while trading 5x Revenants, 10x Chainrasps and 2x Morghasts for 20x Reapers (seems fairly alright).
This means that one GoS chills with the Shroudguard, while the other stays with the Chainguard and the Reapers. The Morghast unit will be able to go off on "adventures" where required.
Sadly I don't have access to the other GoS, so it will have to be two Nightmare Lanterns.