941. Brothers With Their Own Homes in the Same Courtyard
Eiruvin 4:6
Let’s discuss the case of brothers who have their own homes and do not eat at their father's table, as well as wives and servants who do not always eat at their husband's or employer’s table, but rather intermittently, such as in payment for their labor or as a sign of his favor for a certain amount of time. In cases such as these, if there are no other residents with houses in the courtyard, they need not make an eiruv. If they make an eiruv with another courtyard, one eiruv suffices for them. If the eiruv is made in one of their homes, they need not contribute a loaf of bread to it. If there are other residents with them in the courtyard, then each of them must contribute a loaf to the eiruv, just like those other residents must do since they do not always eat at the same table.
Eiruvin 4:7
Let’s say that five groups of people spend Shabbos together in one large hall. If the groups are separated by a partition that reaches the ceiling, it is considered as if each group has its own room or its own level. In such an case, each group must contribute a loaf of bread to the eiruv. If the partition does not reach the ceiling, one loaf suffices for them all because they are considered members of the same household.