...whether the colony becomes more efficient, I do not know. Although I would guess that especially in the beginning the colony benefits from each additional worker.
I gave Serviformicae in the first and second year. Most of the pupae were allowed to hatch, some were killed/fed. Whether this was due to lack of food (which I doubt taken my feeding frequency

) or due to the colony regulating the number of alien workers I cannot say for sure.
I definitely was able to observe different behaviour when I gave the pupae. This brood and Serviformicae already existent in the colony were separated by the sanguinea workers. Maybe to impregnate them with the colony's odour?
In a later state, they live and work together as if from the same species.
This year I did not add foreign brood, though. I want to get a rough estimate regarding their lifespan.
I don't know about your proficiency in German, this is the
link to my diary.