Yosef Karo

“ Paragraph 4 - If the residents of a yard all eat on one table, even if each has his own house, they need no eruv because they are considered like the residents of one house. If they have to make an eruv with the residents of another yard, one eruv for all of them, one bread, is moved to the place where they make the eruv. If the eruv comes to them, they do not need to give part of the eruv according to the rules of a house in which the eruv is placed, because all of the houses are considered one house. ”

“ If they occupy upper chambers, even if the residents of the yard put the eruv in the hall, every group must give an eruv. However, one who has an educator or a scribe in his home, or students who study from the rabbi and live in his house, each in his own room, even if all rooms are open to the yard and each student eats on sleeps in his own room, they do not render others forbidden [to carry] . ”

“ Paragraph 3 - If five groups resided in a hall and divided it up using walls, if they all pass through the other areas as there is only one exit to the yard and everyone must pass through it, only the two middle groups must make an eruv. All the other groups are considered the gates for them. ”