Time for an update.
My first Sumatra Regal pair (#1 & #2) is getting along very well. They are swimming together a lot of times and are also otherwise rarely far apart from each other (would be hard in a 100 gallon tank anyway).
The smaller one is well nourished going on fat and doing fine. It behaves absolutely natural, picking on rocks, algae (and the LPS). It also eats good at feedings.
The larger one worries me a bit. It is still way too skinny and not the best eater at the moment, even though it improved a little. It also often swims back and forth along the front. It is also picking on the rocks, algae and LPS, but still much less than the smaller.
Sumatra Regal #3 is still in the HT, waiting for the ich to die out in the 42 gallon tank and #4 to finish its 60 days of quarantine.
The smallest Sumatra Regal (#4) is the terror of the QT it is in. It chases the dottybacks whenever it sees them, especially during feedings. The only thing the Dottybacks have going for them is that they are small and fast. This is of all my regals the most aggressive. I will try to pair this one with #3.
The two Philippine Regals are fat little pigs and I think they have also grown a bit. As soon as I have a large enough tank for them I will try pairing them up again.