Integrated two flocks

[BlueEggsAndHens]

For about a week during that stage of integration, I leave the pop door propped open at night with a brick. It's just enough of a gap for 4 week olds to fit through (in your case you might have to leave it open entirely, as you said they're "young hens" and not chicks). Obviously don't do it if you feel it's too much of a security issue, but it's an easy way to give youngsters an escape route.

Yeah we have cats and occasional fox so this wouldn't work out.