I was told if a person ate a kezias of a fruit that requires the meain shalosh bracha eg a fig, and another person drank a kezias of wine so is in a suffik about whether to make a bracha achrona. The person who ate the fig can add in the insert for wine in his bracha having in mind the one who ate wine and it does not count as a hefsik in his bracha.
Is this true and what is the source? Thankyou
The halacha is that if someone ate figs and drank wine and he has to make the bracha on two types, (al haetz, and al hagefen) then we say that even though the person listening doesn’t need both, (he only drank wine) it isn’t a hefsek. Even though he is listening to someone say something that he doesn’t need.
In your case however it is the opposite. The person saying the bracha is saying words that he doesn’t have to, and for him it would be considered a hefsek. Therefore he cannot add those words for him. He can eat a fig and then say al haetz and insert al hagefen, even though it is a safek, and it isn’t a hefsek since he needs to say it because of his safek.
Ohr L’Tzion 46-46, V’zos Habracha 5, Sharei Habracha 14-45, 46.