my young hens are 17 weeks old, raised from chicks. they are in my raising pen. I want to add them to the main pen which has 7 hens that are 1 1/2 yrs. old. the pen is bigger 10x20 with a nice amish built coop. I'm very afraid bad things will happen when I add them. planning on doing it at nite. would it be better to let them free range during the day together?