From what I've been told, the bees will actually move brood from one cell to a queen cup in order to raise a queen. I've never seen them do it myself though.they have begun at least 2 queen cells from the bottoms of the frames. I was suprised at the location because I did not realize there were eggs or less than three day old brood in those locations.
Thanks Mike, I don't know why I remembered brood instead of eggs.they move EGGS less than 3 days old to queen cells. good luck,mike