This rather odd pictures shows one of Donna's chicks stretching its wings. This means that you can see how much progress these chicks have also made.
In general, they are running a couple of days behind Rosie's chicks. Perhaps a bit more as although they started hatching two days after the chicks in Box1, they probably haven't been able to get as much food as Rosie's chicks have.
Here you can see that the pins are turning into feathers starting from their tips and working down to the base of the feather. At the moment, they have got about half way there.