Transfering to larger hive

Once all the bees are in for the night, you can move the smaller hive a couple feet away. Bees at night can be quite defensive so dress accordingly. Your other option would be to get up early, say 5am, before the girls are out flying and move the hive then. Stick a branch or something in front of the entrance so they re-orient when they leave the hive (although if you are just moving 2 feet, you may not need to do this step). If the hive needs to move a few more feet away, continue the process every other day until you have reached the distance needed.

As far as moving them to the bigger hive, you should just be able to move the colony from one box to the other without much trouble. Leave the smaller hive in the original (moved) spot with a bar of comb to catch any stragglers, and then come nightfall, move them over to the bigger hive where the rest of the colony is at.

You could just screen in the smaller hive and move it out of the way while you level the bigger hive and get it set up. Then pull the screen and transfer the bees over to the bigger as ruthiesbees suggests. I have done that with a Nuc for the better part of a day, setting in the shade and I poured a little water in every now and again seeing how they were stuck inside.