Vicken,
A couple of years ago, I added 2 frames of bees to my observation hive. To keep them from fighting I put a strip of paper above the bottom/original frame of bees to safely combine them. Right after I had put the hive back in the house, I saw a ball of bees above the paper. The queen had moved up while I was closing it up. I thought for sure they were killing the queen. Later that night, I saw the queen laying eggs above the paper. It turned out that her bees were protecting her from the new bees until she was accepted by them.
Jim