Sorry, but not at all confident of the advice given so far!

Putting the box of brood frames below the brood would allow the bees to clean up the frames from within the hive – so no risk of spreading disease all around the area (particularly getting into your colonies from other infected stocks!) or of setting up 'robbing' from your hives.

Putting brood frames into effectively two supers is encouraging wild comb on the 'short' brood frames or to get more nectar stored in those frames, if, as you seem to say, there is a good flow coming in.

The risk with my method is one of getting brood in the box you want cleared or wild comb on the brood frames proper.

Done quickly at the right time is the key. If they build wild comb from the upper brood frames or lay in the bottom box, they obviously needed more brooding space. Otherwise arrange for Q/E above the box (and a small eke above, with an entrance) and close off the bottom entrance).

You could confine any drones (Q/E fitted, but still using the original entrance), in the hive, but I do not do that sort of thing unless really needed and only for a short period of time.

Hope that helps, and explains the very real shortcomings of the other suggestions.

RAB