Hi @cathiemac,
I think you may have done what I did (correct me if I am wrong), in that you left the split which will make the emergency cells, in the position of the original strong hive, and you put the old queen in a hive in a new spot. I did this because I read it was a good idea, in that the new split that has no queen (and thus quite a long gap between the emergence of new bees from any new queen to bring the colony back on track) would stay strong with the foragers coming back to it. The problem with this strategy seems to be that the field bees keep the colony so strong that it will possibly swarm - after all it has many queens.
I found that when I opened the hive up to have a look at what was happening, those guard bees that @Dee advises about, get distracted from their duties and the imprisoned queens burst forth from the cells right before you eyes and with great urgency. Many queens are then free.
I am confused about checkerboarding as I thought that was something done with the honey frames not the brood frames?