The gemora says that one can bench for all if they are reclining or if they all say lets sit and eat, but if they don't say that and they start eating at different times and during the time they eat they talk with each other is it as if they are eating together and could they make a mezumon?
hananiah lasker, philadelphia,pa - amsterdam,holland
Shalom
The Ruling I received from a top Posek in Yerushalayim is as follows. It depends on whether the people are actually eating together or they just happen to be next to each other. For example, where people are eating at a restaurant, if they really have no connection to one another, it cannot be considered K'vi'us. Eating in a communal dining room (e.g. yeshiva) would be considered k'vi'us, since all the members are actually part of one group, unlike the restaurant case, where each person/party is to himself/themselves.
Yehuda Landy