From "The Hive and the Honeybee" - Management of package bees :
"There comes a critical time in the progress of the package colony, usually about 3 weeks after it is hived when the new brood produced from the eggs of the queen reached a relatively high point in proportion to the number of adult bees. Many of the (package bees) will have died, and no young bees will have emerged. It is often at this time that supercedure ... occurs..., probably because the population is out of balance. This can largely be overcome by giving the package colony a comb of emerging brood and bees from a healthy colony, placing this comb next to the brood combs in the package colony. This should be done about two weeks after the package is installed; colonies so treated will gain surprisingly in strength."
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I do this all the time. Sprinkling a little syrup on both the new frame of brood, and across the top of the package colony brood frames greatly enhances the introduction. "Surprisingly" is an understatement, in my experience. I've frequently seen packages pack in 100-150 lbs of surplus in the first season.
The key seems to be "the population is out of balance...". Sometimes tearing down those queen cells gives the bees just enough time to re-establish the balance. Other times it can be disastrous - for example if the reining queen is already gone. Michael is
probably right - perhaps the best thing to do is to just let them sort it out.