Perhaps my earlier description was unclear, but the one that had been sitting in nesting boxes for many hours per day is the one that got up our of her bedding box and chased another hen out of a nesting box that wasn't even the one she was laying in!
The ridiculous part of all this egg maneuvering is that two different chickens have been caught moving Hei Hei's eggs back and forth today. I'm afraid they're going to end up cracking it.
The other night I found one egg on the ground, so I'm wondering whether these nesting box guarding antics are going to cause some of my girls to lay them outside which would not be ideal.