Case:


Ruling: This case is related to the following statement of the Rama (Choshen Mishpat 264:4). If two people were in jail and one paid money which caused the two of them to be freed, the other one has to reimburse him appropriately. If it is determined that no extra money was added to get the second one out, then the second does not have to pay him unless the first made the payment specifically with the two of them in mind. The Netivot Hamishpat (264:6) explains that the reason the second one has to cover his part is that the first one could have forced him at the time to pay the expenses that were being outlaid.
Even according to the S’ma (264:13), who says that the second prisoner can argue that he could have gotten out without his friend’s help, he can only claim this at the time he was already extricated. In this case, pl has been appealing to def for three years either to pay or to present an exemption, and therefore the payment that they made on behalf of the two of them should need to be reimbursed. There is a halachic limitation that could be considered here based on the concept of mavriach ari, that if all A does on behalf of B is remove a problem that could potentially have affected B, then B does not have to reimburse A. However, in cases where there is no reason to believe that B could have extricated himself (e.g., he owes money to a non-Jew - Rama, CM 128:1), he does have to pay - and here, there is no reason to believe that after ongoing failure in their efforts to garner an exemption, def would succeed now.
There is another reason to obligate def here. All indications are that, historically, pl let def have a room in the building, which had been given to pl. It does not make sense that they would do so under such circumstances that pl would be paying def’s rent. Therefore, even if we could not obligate def to pay (which, apparently, we can), if def is not willing to pay, pl can ask def to leave the premises.