Your attitude is commendable in several ways. You are willing to compromise to avoid litigation, recognizing that it is usually unpleasant for both sides, and you seem aware of the fact that any adjudication should be before a beit din, regardless of your chances to win.[1] We wish more people had your approach, and we are happy to share the halachot regarding your situation.
Regarding the choice of a beit din, if the sides have different preferences because they live far from each other, the defendant has precedence.[2] When the lack of agreement has to do with the sides’ feelings towards the different batei din, the accepted practice is also to prefer the beit din chosen by the defendant.[3] However, neither side can force the other to accept a beit din that he opposes. Rather, in the case of inability to agree on a beit din, the system of zabla, in which each party picks a dayan and the two dayanim select a third, is employed.[4]
There are two primary limitations on invoking zabla. One is that if there is a “set beit din,” whose authority is accepted above that of any other beit din in the area, the set beit din has jurisdiction.[5] This situation is generally uncommon in major, contemporary Jewish communities.[6] Additionally, if the beit din that sent the summons feels that one party’s “zabla dayan” is unfit to serve in that role, they can disallow him.[7] (In practice, zabla panels nowadays often cause a host of problems, and unless it can be done properly, it should be avoided.)
In any case, the staff of the first beit din act as the “point men” until a valid panel is chosen for the purpose of binding adjudication. You should respond to them promptly and respectfully and follow their procedural instructions unless there is a reason to suspect their basic credentials. Although you need not accept them to hear the case, it is not necessarily wise to discount them as a possibility just because the other side turned to them.
In theory, Halacha does not require a hazmana to contain any more information than the identity of the plaintiff and the beit din and the time and place of the hearing.[8] In practice, many batei din expect the sides to present their respective claims and counterclaims in significant detail prior to the hearing in order to make matters run more smoothly. The question arises when the defendant demands information that the plaintiff is unwilling to divulge before the hearing. The B’er Sheva[9] infers from the concept that “one does not divulge all of his claims outside court”[10] that one is not required to divulge any details of his claim. The rationale is to not allow the defendant time to fabricate a defense. The Shach deflects the B’er Sheva’s proof and explains that a defendant has the right to know something about the case so that he can consider complying with the plaintiff’s demands rather than go to court. Most poskim[11] accept the Shach’s opinion.
How much detail must the plaintiff divulge as a response to the defendant’s demands for information? Does it apply to the amount of money, as you inquire? The Shach’s reasoning certainly applies to the amount of money in question, which is crucial information for the defendant in order to determine whether he will bother with adjudication. In fact, the Urim[12] says that even those who do not accept the Shach’s opinion agree that the plaintiff must at least divulge the amount of the claim. It also follows that the plaintiff needs to tell the defendant what event allegedly made him financially obligated so that he can make an informed decision. The plaintiff certainly does not have to divulge his evidence.[13]
In summary, while the beit din’s hazamana appears legitimate, you can ask to go to a different beit din,[14] and you can make your response dependent on knowing the extent of the plaintiff’s demands.