Personally I'd bump the hen down to 4', and put the chick on the roost with her. She wants to roost, fine, but she wanted a baby too, so she can stay with the kiddo for another few days.
If roosts were lower overall the chick would've likely joined her on its own, but it probably needs a bit more feathering to get up to the 4' mark.
If roosts were lower overall the chick would've likely joined her on its own, but it probably needs a bit more feathering to get up to the 4' mark.