I've got some ISA hens. I've found that as lovely they are around people they can be very problematic when it comes to integration. It took me 9 months to integrate 6 ISA hens to the rest of my flock! I've just integrated 7 10 week old marans and Araucana to the flock. They have been in a growout pen for a couple of weeks in the main run first. I've not really had any problems apart from one of the ISA's. I separated her a couple of days and she soon got the idea! They can be difficult but persevere with it. If your Araucana is happy with the chicks introduce them all together when there a bit older. Safety in numbers! Araucanas are such sweet hens.