If one hears kiddush in shul and eats some cake to fulfill kiddush be-makom suedah on shabbos morning, Should one repeat kiddush at home during the meal (in a case where everyone already heard kiddush) or do we say there is no reason to repeat kiddush once everyone already heard it at shul?
The Shulchan Aruch (273:5) rules that one can make kiddush and fulfill the requirement of kiddush be-makon se’udah by drinking a cup of wine, and according to a number of authorities (Ginas Veradim 3:12; Magen Avraham 273:; Mishnah Berurah 273:25) the same applies to mezonos. See also Ein Yitzchak, Orach Chaim 12.
There are some who write that wine is possibly more important (than mezonos) for the purpose of kiddush, and others who maintain that one should make kiddush specifically on bread (the Vilna Gaon). The Mishnah Berurah thus writes that one should not rely on mezonos for the Friday Night kiddush, but make kiddush before a bread meal.
The Magen Avraham (273:9) writes that after kiddush has been made on wine, one does not have to make kiddush again before the meal. The reason why this is not obvious–the Shulchan Aruch writes that one fulfills the obligation of kiddush–is that it is possible that even after fulfilling the obligation of kiddush, one should make kiddush before the meal, ‘in honor’ of the Shabbos meal.
In his Mo’adim U’zemanim, Rav Moshe Sternbuch thus writes that it is preferable to do this (make kiddush again before the meal), in deference to rishonim (he quotes from the Raavad) who write that kiddush is required before the meal. However, most do not have the custom of repeating kiddush after everybody has made kiddush in shul.