A neat little trick - use two small push-in cages to isolate the queen cells, sacrificing the middle one, or every other one if they are clustered. Let them hatch, release them one at a time into different mating nucs.
They need to be placed so they cannot sting eachother. Also, mark the frames so you can quickly check them, or put the frame into a nuc and mark the nuc.
Form these cages out of #8 hardware cloth around something (a dowel, a pipe, a PVC tube, etc.) the size of your thumb, cutting the bottom off to leave as much wire pointing down as possible (~1 whole square). Make sure there is room for them to hatch. Some frame and/or comb surgery may be in order. This should get DanielY somewhat busy....
Daniel - Congrats! Nice learning curve.
Challenger - Sometimes a virgin or a newly-mated queen drifts into your Cell Starter or Cell Finisher colony. Most any queen will sting the queen cells, and the house bees will tear them down. Entry blockers made of excluder have been suggested and used to prevent this.