The law by guests:[1]

The entire law above in which one may be required to repeat or recite a new blessing over a second food due to it not being included within the blessing that was recited over the first food, only applies to an individual who is eating his own food [i.e. at home, in a restaurant, etc]. However, one who was invited to eat as a guest on another person’s table, never repeats the same blessing over any subsequent food even if he was unaware that this food would be served.[2] This applies even if the original food has already been eaten, and the second food has no similarity to the original food, but simply shares the same blessing. However, if he was not invited as a guest and simply showed up to the table for a temporary visit then he must repeat a blessing for every food that he is given, even if it is the same food, even if he has yet to finish his first food.[3] [However, if he plans to stay for the meal, or was invited to partake in whatever food that he wants, then this follows the same laws as a regular guest.]

Chashuv foods:[4] It is questionable whether the before blessings of a guest covers also the more significant foods that the host will serve them. Accordingly, in order to avoid the above question, it is proper for the guests to explicitly have in mind to exempt also the more significant foods.

• For example: If a guest recited a Shehakol on a cup of tea that he was served, then the blessing of Shehakol is not to be recited on any other food that he is served which receives the blessing of Shehakol, such as meat, fish, chicken, cheese, etc.
• For example:[5] If a guest recited a Haeitz on an apple that he was served, then the blessing of Haeitz is not to be recited on any other fruit that he is served.
• Hotel or school dining room, reception:[6] Those who eat together in a dining room, such as in hotels and educational institutions who serve breakfast or lunch or dinner, are not to repeat any of the same blessings on subsequent foods, being that when they say the blessing on one food, it includes all the other foods being that they are similar to a guest who is being fed by his host. The same would apply by a guest who attends a reception such as for a wedding or Bar Mitzvah, that even if he does not wash on bread, he is not to repeat the same before blessing on any subsequent food or drink.
• Kiddush in Shul:[7] When attending a Kiddush in shul after Davening he is not to repeat the same before blessing on any subsequent food or drink. Thus, if he already said Mezonos on a cracker, it should not be repeated upon eating the Kugel or Chulent later on. Likewise, if one already said a Shehakol on a food or beverage, it should not be repeated upon eating meat that is served later on into the Kiddush.
• A husband who is served by his wife or children:[8] A husband and father who is served by his wife and children seemingly does not have the same status as a guest and must repeat the blessings in accordance to the laws delineated above, as he is the true decider of what he will eat and what he will not eat, and hence it is not considered as if he has all the future foods in mind.[9] However, some Poskim[10] rule that he does have the status of a guest in this regard.

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[1] Seder 5:8 [When present at the meal of a host, the blessing one says on the fruits [or any other food] includes all future fruits of that blessing.]; 9:5 and 8; 12:13; Luach 6:5; 7:8; Admur 174:10; 179:7; 206:9; Michaber 179:5; Brachos 42a; Hagahos Rabbeinu Peretz on Tashebitz; Tosafus Brachos 42a; M”A 179:7; Ketzos Hashulchan 56:2; 58:12; Piskeiy Teshuvos 179:8-9

[2] The reason: As guests naturally have in mind when they recite a blessing for it to cover all future foods that will be served which share that same blessing as they initially come with intent to partake in the menu that will be served by their host. Hence, it is considered retroactively as if they already had it in mind at the time that they recited the blessing. [Admur ibid in all sources; Taz 179:3]

[3] Seder 5:8; Luach 7:8; Admur 179:7; Michaber ibid; Rama 174:5; Tashbeitz 300; M”A 179:6

The reason: As when he said a blessing on the first food he did not have any knowledge as to whether he would be offered another food. [Admur 174:10]

[4] Ketzos Hashulchan 56 footnote 6 that so is implied from Admur ibid and 206:9-10

[5] This is the example given in Admur Seder 5:8; SHU”A 179:6

[6] Aruch Hashulchan 179:6; Piskeiy Teshuavos ibid; Rav Elyashvili in footnote 51 on Seder ibid

[7] Rav Elyashvili in footnote 51 on Seder ibid;

[8] See Biur Halacha 179:2 “Ad Sheyomar”; Piskeiy Teshuvos 179:8 footnote 41

[9] P”M 179, brought in  Daas Torah 179 and Biur Halacha ibid; Rav Elyashvili in footnote 51 on Seder ibid; See

[10] Aruch Hashulchan 179:6; Ashel Avraham Butchach; Betzel Hachochma 6:69; Piskeiy Teshuvos ibid;