2,781. Mutually-Prohibited Partners

Hilchos Nedarim 7:3

In the previous halacha, we said that two people who are prohibited to benefit from one another may not use the communal property of their city. In order to permit use of these things, each of them should sign his share over to the governor or to someone else, and that share should be acquired for him by a third party. The result is that when person A or person B enters the communal bathhouse or the shul of their city, he’s not entering the property of the other party because each of them has renounced his share and given it away.

Hilchos Nedarim 7:4

Let’s say that person A and person B jointly own a courtyard. If it can be divided, they’re not permitted to enter it until it’s divided, at which point each may enter his own share. If it can’t be divided, each of them should enter his house, saying that he’s entering his own property. In either case, neither party is permitted to put a mill or an oven in the courtyard or to raise chickens there.