Those chicks may be too big for 'tiny doors'.....but it's something more to buildOthers with more experience (@aart) will chime in. My experience was similar but allowing the chicks to mix with hidey holes, obstacles, etc will soon dissuade the older hens from chasing shadows.

Complicating matters is that there's no run(?), chicks will need to learn to get back into coop.
This is how I do it:
https://www.backyardchickens.com/articles/integrating-new-birds-at-4-weeks-old.72603/