Brief update. The brotherly love thing did not last. The two females have staked their territories close to the two caves I put at the opposite ends of the tank. They seem to stick to their cave area, and do not engage each other. One of the females colored up, and started being aggressive with the dominant male (courtship?). The dominant male, in turn started chasing the lower male around the tank. There didn't seem to be any serious physical engagement. I gave it a day, but when I noticed the lower ranked brother spending time at the top half of the aquarium, behind the filter inlet, I figured he is very stressed. So I moved him to the main tank. My 23G has the dominant brother with the two females, and I no longer see aggressive chasing - except the coloured up female occasionally charges the male. The second male is in the 40G with a honey gourami, rasbora, green neons and panda cories. Speaking of the panda cories, they had more babies - there are once again 1/2" long small fry in the tank. The older fry are now at almost an inch. They are a happy bunch apparently.
One question. I do not have any caves in the 40G for the male, though it is very densely planted - jungle like. Do I need to give him a cave, or given that there are no females, are the dense plantings sufficient?