No people do that all the time and when they all wake up in the morning they think they were already there to begin with. This is what I've heard from others who have tried it.
When I get pullets even week old chicks, I put them in the free range run (4000+ SQ FT) with the older ones. They always accept the new ones. Sometimes there's a squabble or two, But I provide several hiding places. I usually make little tiny teepees and brush piles with sticks from the woods...