First and foremost, mazal tov!
Traditionally, a shadchan is paid – like an agent in various fields of endeavor these days. The Rama[1] raises a question only of whether one pays at the time of the engagement or of the marriage. The Rama’s rule, one of the main rules in monetary law,[2] is that we follow the “minhag of the state.”
As we know in many areas of Halacha, the local custom is not always determined by geographic grounds. When dealing with monetary law, one has to consider the appropriate milieu for determining what unspoken assumptions people were working under. In some issues, the assumptions of different segments of the population are clearly defined, certainly including the Charedi community in regard to a shadchan’s fee. In that community, the widespread practice is to pay a shadchan, whether a professional one or even a mutual friend. There may be different practices concerning how much to pay, and there may be certain conditions, but $1,000 per side is quite standard.
The fact that in the Dati Leumi/Modern Orthodox community, a shadchan does not usually get paid, other than by receiving a present at the couple’s discretion, is fine.[3] According to the Rama, the minhag is the determining factor, and clearly this applies to whether there should be payment at all, and not just to its conditions.[4]
Your question relates to the broader question regarding when two people from different communities with different practices happened to interact without prior discussion. We dealt with this question in a different context in an Eretz Hemdah court ruling.[5] Without getting into the details, we explained that the matter depends upon the reason that having to pay for a service without explicit agreement is based on custom. Is it because of an assumed agreement or because of the benefit one received? However, that issue is probably not relevant here. If your daughter operated within the Charedi “shidduch scene,” she was bound by its rules unless she specified otherwise.
Formally, it is unlikely that you specifically have to pay, as your daughter is the one who “hired” the shadchanit, not you. While parents usually pay for such expenses, your daughter did not act as your agent unless you gave her carte blanche for all dating-related expenses. For that matter, you are not obligated to finance the wedding (although Chazal did expect it[6]). However, if you do not pay, then your daughter must.
In the Charedi world, there is a belief that not properly fulfilling an obligation to a shadchan is a bad omen for the marriage. We are not experts on bad omens and will neither confirm nor dismiss this concern. In any case, monetary obligations must be paid based on Halacha and ethics. One difference that may result from one’s belief about the omen, however, relates to whether it is a good idea to ask for a delay in payment. It is halachically legitimate for one who has difficulty paying immediately to ask for a delay (although caterers and photographers rarely agree), but many avoid doing so with a shadchan. Depending on family dynamics, this might be something to discuss with your daughter.
We understand that it is hard enough to pay for wedding expenses that one expects, and it is upsetting to have surprises of this nature thrust upon the scene. On the other hand, the fact that this wedding is catering to a different clientele with different standards than you are used to does present some opportunities. For example, you can find out about ways to save money on things that you are accustomed to but are not necessary in your daughter’s new circles.
We do not need to tell you that life brings unexpected expenses, and it is better that those be related to joyous events than other types. Even without surprises, many people have real trouble paying for weddings, and many difficult decisions have to be made regarding priorities and means of obtaining funds. Tefilla is one response, and “Hashem has many messengers.” Those who are truly in need are allowed to ask for and receive financial help from outside the family, and certainly from within it. However, we must emphasize that whether or not the shadchanit needs the money as badly as you do, someone has to pay her.