and Welcome To BYC! Sorry for your loss. You'll probably have to give them an introduction period ... seeing but no touching through wire seem to work best, ie dividing the coop into two sections or keeping the new/younger ones in a cage inside the coup for a couple of weeks to a month at least. The chickens will get to know each other and sort of work out a pecking order before actually coming in contact with each other. Letting them free range together is a good idea and should help... It will take a couple of weeks to get the pecking order sorted out. There is a nice article in the Learning Center on integrating flocks you might like to check out, (the part about actually combining them is after the quarantine section, depending on where you get the new birds, you may also want to do a medical quarantine) https://www.backyardchickens.com/a/adding-to-your-flock and nice article on the see-but-no-touch into method https://www.backyardchickens.com/a/introducing-new-chickens-using-the-see-but-don-t-touch-method
