One of my hives are not filling out the brood frames all the way to the outside frames. Can or should I rotate the frames to the middle?
what you suggest is doable, but it does need to be done with caution.
I call this process opening up the brood nest. any number of things might keep a hive from expanding horizontally. a frame with foundation or a drawn frame with significant pollen or even capped honey can act as a barrier to brood expansion (in the verticle plane).
I would not suggest that you boldly rotate frames to the center of the brood cluster since you do take the risk of introduing your own verticle barrier which has the possibility of encouraging superscedure (by splitting the brood nest*). I typically spread the brood nest somewhat by incerting pulled frames along the edges of the brood nest and shuffling frames heavy in pollen or capped honey to the outside edges of the box.
*you can accomplish something along the same thing horizontally by splitting two brood boxes with a box heavy in stores. with any quantity of space sepearting the two brood clusters the box that does not have a queen will on occasion begin rearing queen cells.