Since you only have a total of 12 maximum number of brood frames, it seems to me that pulling out all the honey and pollen from the three boxes, then condensing the brood to 6 frames centered in two boxes and putting two frames of honey and pollen back on each of the outsides of each box would be the way to go. Keep the honey for surplus and store the pollen for later use. Since you are in a nectar flow, there should be plenty of honey and pollen production right now without those frames you took out.