Of course I had to open the hive bodies to do so & noticed last night a handfull of bees on the underside of the bottom board on both hive bodies. Just now I checked & bees are still on the underside of the bottom boards.
Do you have a picture? I'm a little confused (very easy for me!) about how you're seeing bees underneath the bottom board by opening the hive. Do you hives not sit on a stand? Is there an opening that is allowing them to go underneath the hive?