The prospect of integrating new chickens into an existing flock is always nerve-wracking, whether they're 8 weeks old or 8 months old. The main concern is that the two groups of chickens will not get along. However, it is possible to introduce new chickens to a different group of birds without drama or bloodshed. Integrating new chickens into an existing flock does not have to be stressful for the chicken keeper or the chickens.