I've tried several methods of overwintering nucs but only one gives a high success rate. I divide a hive body into 3 compartments with something similar to a follower board and establish a 3 frame nuc in each of the 3 compartments. The nucs are started and kept on top of a strong and well established 2 story colony. Heat from the colony rises to keep the nucs alive. They have to be checked 2 or 3 times during the winter and additional combs of honey given if required.