Integrating two flocks

[LIsaajb]

We have 6 RIRs that are 3.5 months. We're having a friend's flock of 2 RIRs and 3 sex link move in while she's away starting this week until August. Her chickens are about the same age as mine. How can we make sure that the girls make friends and behave themselves? My girls seem to be fairly friendly, but I want to be careful just incase someone gets anxious.

 

[LIsaajb]

Also! Is there a way to mark them so we can tell them apart?

 

[fried green eggs]

Can you divide the coop and run so, they can get acquainted through the fence for the first week? They will still need to get pecking order decided after that but, should be a milder form of pecking to accept the new ones.
To identify you can use the small 4" zip ties - can be put on leg loosly. Cut excess so it won't tighten down more.