Mommamia: I think the Poskim discuss that. I don’t recall what they say. And there’s no disrespect in serving the child first if the guests know the Halachah (assuming that this applies to a Kattan; not positive about that).
I once did hear a very prominent Rosh Yeshivah say that it’s B’feirush in the fifth Chelek of Shulchan Aruch that even a Kohen has to help his wife out around the house.