I had a beekeeper that had his bees flying around the front of his hive in large numbers. He felt swarming was imminent. He called me and asked what he should do. He has several hives.
I told him to got out immediately an switch the swarming colony with a weaker hive. So he moved swarm Hive A to weak Hive B. Then weak Hive B to swarm Hive A. He then went through the hive that wanted to swarm and removed the swarm cells. Now the field bees fly back to where they think they live. Hive B the weak one, gets all the field bees from Hive A and now gets stronger. Hive A the strong hive gets the field bees from Hive B and now gets weaker. This solves swarming issues immediately. Now Hive B needs to be watched for swarming because it will be stronger.
The beekeeper was lucky he was home and saw this in the morning. By noon the bees may have swarmed.