Is poking some food into the nest when the female is out an option?
Just tried with a couple of small meal worms but when she returned she took them back out.
Looks like we are probably about to loose one of them. He us sinking to the bottom of the nest, not opening his beak for food, not really putting up much of a fight.
The other three still look OK but I still don't think they are getting enough food. She is still taking 10 - 15 minutes to find each caterpillar and then resorting to peanut butter which she can't really get off her beak and in to their mouths because its too sticky.
The oldest is showing some signs of development since yesterday. He has more feathers and more coloring.
One of them keeps getting out and going for walks around the box before he either falls back in to the cup or she drags him in.