You'll get lots of opinions on this post... here's mine...
It depends. What is your goal? Do you want to make honey? If so, concentrate on maximizing the bees in your two hives while minimizing the likelihood of swarming - you want as many bees as possible in your honey hives - you don't want to reduce their population. Control swarming by managing congestion in the brood nest (probably too late for checkerboarding at this point if you haven't done it already, but that's a whole other discussion...), not by reducing the number of bees in the hive.
Just out of curiosity, why are you concerned about boosting your packages? They won't make honey this year, and it takes time for them to build comb, lay, raise workers, build more comb, lay, raise workers... If I had four packages with no comb to put them on, plus two strong hives, I would be concentrating on making honey with my two hives, and making sure the packages are well fed (or on a strong flow/pollen) and have all the resources they need to draw comb and raise bees so they build up and draw comb adequately this year.
If you are willing to sacrifice some of the honey-production of your two hives to "boost your packages," one relatively low-impact (to your hives) way to give them a quick boost would be by providing a few frames of drawn comb for the queen to lay in as soon as she's out of her cage. Otherwise I wouldn't worry too much about them - just keep an eye on them and manage any problems that arise when you notice them.
HTH
-Pete