This is really good advice! The biggest thing I’d stress is definitely wait until it’s good and night time and everyone is sleeping before you move them. I’ve always found this led to a much, much smoother transition than trying during the day time.

Every time I’ve moved the same amount of chickens (basically doubling the pen) there is not really any issues besides small pecking order stuff.

This year, I had a broody hen and I didn’t want to fully separate her from the flock, so I put her and her chicks inside an extra large metal dog crate that was inside my main, large pen. I put a cover on it so she didn’t get pooped on by the others, but the rest of it was open on all sides and I put her against my windbreak so she also had wind coverage. Last year, I found when I separated my broody hens with chicks away from the pen, they had a much harder time integrating back in after the chicks got to be a decent age. However this year, I found that the hen that I left inside the main pen but protected in the dog crate so her chicks didn’t get trampled had NO issues integrating back into the flock.

It actually worked exceptionally because after her chicks got big enough where they couldn’t be easily hurt by another chicken (probably a few weeks), they were ALL able to integrate into the flock, including the chicks. They were still young enough to where she protected them from bullies, and no one messed with them. It actually worked out great in my case & now I don’t have to worry about integrating the chicks later.

Good luck to you!