There are times when a rav may permit suggesting a shidduch and temporarily concealing information which could prevent the shidduch from coming about.
Occasionally, a situation exists as a result of which people might be reluctant to even consider a shidduch with a particular person or family, though, in fact, the situation need not warrant such reluctance.
It is in such a case that a rav may permit an initial meeting (and at times even a series of meetings) without the pertinent fact being mentioned, so that when it finally is revealed, the person stands a chance of being judged fairly.
However, it is forbidden to conceal the information until after the other party has developed strong, positive feelings concerning the shidduch, for at that point, the party will be denied the opportunity to reach an objective decision, and will have been the victim of dishonesty and manipulation.
Needless to say, such decisions are not to be made by a shadchan (matchmaker) and certainly not by the family involved. Only a qualified Torah authority should decide such matters.
Sefer Chofetz Chaim, 24 Kislev, Page 216