They have two goals.
Move to their queen, and return to their original home.
If you move the box with the queen, you will get a balance of each, so yes, 5 feet is fine. If you move the queenless hive, I would say a couple miles for the best balance. If, after 3 weeks or so, when in the same apiary, they are not balanced, switch places in the middle of the day. They will then balance out the population, as the returning foragers will go to their known location.