I got a very exciting proof today. Diamond 5 is dominant to Domino 1.
It's a straightforward proof. I mated a Diamond 5 with a Domino 1. The offspring showed the Diamond 5, but I was able to pull the hidden Domino 1 out with a more recessive fur (the toyger tan).
This PLACES Diamond 5 above Domino 1 and it is also recessive to Flame 4, which is in turn recessive to Smokey 5. So this proof slots BOTH Diamond 5 AND Flame 4 right above Domino 1 and below Smokey 5.
Only Genesis Diamond 4 remains to be placed.