Aww. Anything can be done.
The deal is with social structure in the flock. Each bird has it's place among the flock, so when newcomers show up there has to a be a re-shuffle for position. It's the Chicken Way.
They've never heard of our New Age niceties like, "I'm Okay, You're Okay," Everybody Is Unique," and so on. To them it's more like, "Get in your place, and be quick about it!"
And unlike people who (supposedly) work out their differences in a civilized manner, this social ordering/re-ordering is accomplished in only one way:
with a sparring match.
Normally it isn't really harmful, although it can be quite blustery and vocal. Once it's over and the dust settles, each bird goes on to his/her place in the flock.
Next day, everyone is settled in and working alongside one another.
With that said, here's a few thoughts:
1. Yard them near each other, separated by a fence, for several days.
This way they can grow accustomed to one another. There will still be sparring, but this tends to make it more of a formality.
2. Bring them together at night
Do this after the 3 days or so of separate yarding. This is one of those "old tricks," often repeated. Normally, it includes witholding food on the last half of the prior day and then feeding everybody in the coop in the morning (feeding time is bonding time
).
It is no guarantee that all will be well, though. Fact is, they will still probably square off when the sun rises and the feeding frenzy is over. They're chickens, after all, not gravel headed slugs.
But again, their competivie ardor is normally diminished by these steps.
3. Stay close when you integrate them
Sometimes the newcomer just isnt integratable, and will be forced into dead last spot in the social hierarchy. Then the others may pester it mercilessly, often to the point of death.
Stick around when you bring them together - intervene if it turns bloody.
4. Don't expect miracles.
As said in #3, occasionally it doesn't work out. And there is no timetable for the integration - you can't stand there with a stop watch and dictate to them. It's incumbent on you to
pay attention until it's all over, even if it takes a few days.
The biggest problem is when you bring a relative few newcomers into a larger, established flock. It's best of you can reverse that and have more newbies than resident birds.
In your case, with just a small flock, stick close to the outlined steps and you should have a (fairly) smooth transition.