Thanks for the answer. That's what my husband suggested as well so I left them separated while I was at work. I stepped out long enough to feed the dog but that was obviously too long so now I will only do supervised...
How big do they need to be before they can defend themselves and be fully integrated? The crate for bedtime is going to be too small for them soon and I have no other way to separate them at night. The littles are 9 wks old and the bigs are 16 wks old so they are only 7 wks apart but that seems to be enough of a difference.
In hind sight I should have passed on the littles but didn't know anything about integrating and the feed store finally got the ones I really wanted so I bought them. When I bought the bigs the store had no idea if the breeder was sending the Welly Hybrids or not and I couldn't wait to get them due to vacation timing so I bought what they had at the time. I did research what they knew they were getting before they came in though. The bigs are as follows... 2 RIR's, 1 ISA Brown, 2 Barred Rocks, and 2 Austrolorps. We bought 2 of each but 1 of the ISA's turned out to be a roo so he is no longer with us. The littles were my preferred breed but I am happy with the others too.
You really are dealing with tough ages to be integrating which is going to slow the progress - in my opinion. A 7 week age difference is huge when they're this young. Slow and steady is my suggestion. Keep a watchful eye on their progression. You'll definitely know when they're ready and able to be a single flock.