Transfer of Parking Rights in a Shared Parking Lot

Hello, I have a car and there is no parking space in my area. In the building next to me, there are 3 parking spaces that belong to all the residents of the building, and I have a brother-in-law who lives there. On days when he is not at home the whole day, he allows me to park in his space. But the neighbors claim that he has no right to transfer his right to be in his place to me. What is the law?

Shalom!
Since the parking spaces belong jointly to all the residents of the building, your relative does not have the right to let you park there. The partnership only grants him the right to park there himself.