X2! they will fight so try to watch it does not become too intense and any serious injuries occur. they will sort out the new pecking order eventually. Havea 3 month old cockerel who put a serious hurt to a 1 yr old hen. And they are a mellow breed!!SighWhat is the age difference? It will take a few days for them to get along. The best thing to do is combine them at night as it gets dark. When they wake up they will all be together and it will be easier for them to accept each other. You will probably have one older bird that will pick on the younger ones. Be prepared.
I mixed two flocks of 8 week old chicks. Even though they were only 2 days apart in age, they still fought and it took a week for them to start getting along. Most of the time it goes well, but you never know how personalities are going to flare when new birds are added.