Two people arriving together bring two sets of habits, foods, songs and relatives who know entirely different versions of the day. A celebration that quietly runs on one side’s customs can leave the other side polite and slightly outside it. Nobody usually intends this; the familiar simply feels like the default to whoever grew up inside it. Making space for both is less diplomacy than accuracy about who is being celebrated.

If you are planning something like this, go through the day and ask whose normal each part came from. Add one thing that belongs unmistakably to the other side, and ask rather than guessing what would matter.