These German Rollers from my imports are so crowded that they stand on each others backs.
To give them more room, I put an additional nest in the cage and a perch between them.
From about 14 days, even though you think they have not left the nest yet, they freely switch back and forth to the new nest. This morning they were divided three and one. Since that looks crowded, I put one back in the other nest.
Momma roller feeds one nest and then the other back and forth to which ever nest is begging loudest! The noisy ones get fed first!!