Put a feeder on them with the drone comb. Put the drone comb in the center of the broodnest. They should draw it out and queen should lay in it. Put on the feeder to simulate flow and get them to build, these are conditions they will raise drones in.
I would suggest doing it in last half of June when you pull off your honey. Then putting on a feeder will not spoil the honey crop and will inspire the colony to build for drones and queen rearing. It will also give you time to get the nucs built up for over wintering.
I would suggest doing it in last half of June when you pull off your honey. Then putting on a feeder will not spoil the honey crop and will inspire the colony to build for drones and queen rearing. It will also give you time to get the nucs built up for over wintering.