You have a few options.
Swap places with your two hives, the strong one will lose field force and the weak one will gain it.
Take a frame or two of sealed brood with adhering bees, without the queen of course, from your strong hive and give to the weaker hive.
Shake in nurse bees from off a frame or two of open larva from your stronger hive. Once again, keep track and don't shake in the queen.
What you do will depend on just how strong the stronger hive is, can it afford to lose brood or can it afford to lose field bees. I myself tend to lean towards giving brood frames and nurse bees, instead of switching hive positions, when these situations such as yours happens.
Swap places with your two hives, the strong one will lose field force and the weak one will gain it.
Take a frame or two of sealed brood with adhering bees, without the queen of course, from your strong hive and give to the weaker hive.
Shake in nurse bees from off a frame or two of open larva from your stronger hive. Once again, keep track and don't shake in the queen.
What you do will depend on just how strong the stronger hive is, can it afford to lose brood or can it afford to lose field bees. I myself tend to lean towards giving brood frames and nurse bees, instead of switching hive positions, when these situations such as yours happens.