Adding hens with a rooster into an all hen group

[Kenzie22]

So, a little while ago my newest and youngest group of hens started laying eggs, there are 4 hens and 1 rooster. I have 15 other hens in a larger pen than what those that started laying were in. Can I add the 4 hens and 1 rooster into the other flock of 15 hens or will the rooster try to kill all of the others? What will happen if I do this?

 

[DobieLover]

He wouldn't try to kill any of the others. He will want them all for his harem and, depending on his personality, will either try to win them over or force the issue. His current head hen will likely be a tyrant to the new hens and may peck their heads while he is breeding the new ones.
You should still do a "look don't touch" introduction for at least a week for both groups to be exposed to each other before you allow them to intermingle.

 

[Catastrophic]

Like @DobieLover said the rooster wouldn't kill the hens. All that would happen is that the hens will have to reestablish their pecking order. This means the hens will peck the new members of the flock and maybe deprive them of food and water for a few days while they are reestablishing the pecking order.

 

[Kenzie22]

Okay. The coops right now are right beside each other so since the littler ones have been in a chicken coop, they have all been able to see each other. There is still chicken wire in between them but they have kind of already had the look don’t touch. Also they roost right beside each other in different coops.