528. Does Bentching Cover Kiddush Wine?
77:10 The Kiddush wine is considered a part of the meal and therefore it does not need its own concluding bracha, being included in the bentching (even if one did not drink wine during the meal itself - Mishnah Brurah 272:38). Some authorities say that the Kiddush wine is not included in bentching, so it is advisable to act stringently and, after bentching, to recite the bracha over a cup of wine, drink at least a revi'is (3.3 ounces), and say a concluding bracha on that with the intention that it also includes the wine he drank for Kiddush.
77:11 There is no need to recite a bracha on any wine drunk during the course of the meal, as it is covered by the bracha of hagafen that was said as part of Kiddush.