I often get questions that go something like this: Is it alright to add a brood box above a super? Or, I only have supers, can I use those as brood boxes? People are worried about whether they are using the "right" size of box.
This is a concern for people, not bees. The bees don't care what size the boxes are. They don't get their little tape measures out and measure the box height and say "Well, this is a deep box, so we must use it for brood". Or, "this is a western style medium box, so we must only store honey it it". They perceive a space, not a box size.
March is one of the hardest months for bees. More beehives starve in March than they do in January and February. Why? Because they are not doing much in Jan. and Feb. so they are not eating much. Just trying to stay warm. How-ever, in late February or early March, they start rearing brood to prepare for the spring harvest of nectar and pollen.