57:5 If one recited shehakol over beer with the intention that it should also cover everything else that would be brought to him whose bracha is shehakol, he does not need say another bracha if they bring him fish. However, if he had no particular intention, even if he still had beer in front of him when they brought him fish, he must recite a new bracha. This is different than the case of produce where, even if one is eating apples and nuts, they are both still fruit. Beer and fish, however, are two completely different types of items, one being a food and the other a beverage. Therefore, one cannot cover one with the other’s bracha unless he had both items in front of him when he said the bracha, or he had specific intention to include both.
57:6 This rule only applies when one eats his own food. If one is a guest at another’s table, the bracha he recites over one type of food includes whatever he will be served, even if the first item is gone by the time he is brought subsequent courses, since everything depends on the intentions of the host. However, if one had intent to act in a particular way when he said his bracha and he changes his mind, then he must recite a new bracha. If the host did not plan to serve more food but ended up doing so at the guests’ request, they do not need to recite a new bracha. Even though the host did not intend to serve these items, there is a presumption that a host will probably give his guests whatever they require.