A week on, and the last two females are doing well. They are both eating flake or pellets, not sure which as I feed both and crush them up for my very small fish so I only see them eating bits floating in the water.
I have seen them flaring at each other, and the smaller one is showing great interest in the cavity in the mangrove root, the tall thin piece of wood in the tank. You can see the top of it in the last picture in the first post. I find this behaviour most interesting as I didn't think females bothered with caves unless tempted in by a male. I am watching this smaller fish with interest as I've previously had a 'female' which developed male characteristics at puberty. This is one reason I'm not rushing to find any more males just yet. Though this one is showing female traits - non-lumpy forehead, black edge to the anal fin, and anal & dorsal fin not extending to the tail fin. I'll have to wait and see and maybe look for males in a few weeks.