I've been adding bees to my weaker hives lately. The source is a cluster that resulted from an interesting trapout situation, so they're queenless.
While I was using the newspaper combine method, I recently came to the conclusion that this is completely unnecessary.
Why? The queenless bees don't seem to be recognized as foreign in the hives where they've been introduced. Similarly, the introduced bees have no beef with bees in the adoptive hive.
It must come down to a lack of queen/nest recognition pheromone on them?
I'm gonna try a direct dump next time to test this hypothesis.