Responsa for Bava Kamma 231:8

Q. A believed that his brother's (childless) widow had retained from her husband's estate more than the amount due her for her ketubah, and he refused to go through with the ceremony of halitzah, unless she paid him some money. They finally agreed on the sum of 20^*In Mord. ibid. L. ibid. the reading is — 2 marks. marks. Before the ceremony of halitzah she gave the money to a trustee in A's presence. A said to the trustee: "After the ceremony, you must give me the 20^*In Mord. ibid. L. ibid. the reading is — 2 marks. marks". To this, the trustee replied, "I shall." After the ceremony, the widow produced her ketubah, swore that she had not received enough to cover same, and demanded the 20^*In Mord. ibid. L. ibid. the reading is — 2 marks. marks back. The court decided that the 20^*In Mord. ibid. L. ibid. the reading is — 2 marks. marks belong to the widow. Is the decision of the court correct?
A. The question is not sufficiently clear for us to express an opinion. If the widow told the trustee, in A's presence, to give the money to A after the ceremony, the money belongs to A; since this money is simply a gift which the trustee received for A's benefit. But, if the widow said nothing while she gave the money to the trustee, A's words are of no avail, and she can reclaim her money in payment of her ketubah.
SOURCES: Cr. 65: Pr. 30; L. 339; Mord. Yeb. 24.

Q. A matchmaker was promised two marks should he succeed in concluding a certain match. He was successful in his efforts. Is he entitled to the full two marks?
A. The matchmaker is only entitled to reasonable compensation for the time and effort he has spent. However, if because of his preoccupation with this match, he was hindered from devoting himself to other matches (from which, it is reasonable to expect, he would have earned a similar amount), he is entitled to the two marks.
SOURCES: Cr. 123. Cf. Pr. 498; ibid. 708; ibid. 952; L. 308; Mord. B. K. 172; Agudah B. K. 140.

Q. Is a matchmaker entitled to collect his full fee [even if it is out of all proportion to the time and effort spent in consummating the match]?
A. A person who is not a professional matchmaker is entitled to compensation in accordance with the time and effort spent in concluding the match. But, a professional matchmaker is entitled to his full fee since he could have earned the same amount had he devoted his time and energy to another match. However, even the professional matchmaker is not entitled to his full fee unless it be almost certain that he could have earned the same amount from another match. Thus, the case came before me of a matchmaker whom a man promised a sum of money upon successfully concluding a match between himself and a certain woman. After the match was concluded and the man paid the promised sum to the matchmaker, the latter demanded a particular sum from the woman, claiming that she had also promised to pay him a fee. The woman denied his claim. I freed the woman from obligation for the following reason: Even if the woman promised a fee to the matchmaker he would not be entitled to collect it since he occupied himself with this match because of the money promised to him by her husband. The woman's promise of a fee to the matchmaker and the effort he spent as a consequence thereof, did not deprive him of any income, since his time had to be spent anyway on consummating this match.
SOURCES: L. 308. Cf. Agudah B. K. 140.