Chelkas Mechokek (2:5.9): One who knows that there is a mamzer is not allowed to reveal this information – But it is stated in Shulchan Aruch (EH. 2:3) that two people had testified that a family has a mamzer or challel. How can they do this since they are violating the halacha of not revealing this information? However saying they shouldn’t testify also presents a difficulty since we pasken in this sif that if there is a doubt whether there is a mamzer in a particular family that someone who marries a member of that family needs to get divorced – so why isn’t it a mitzva to reveal this information because today or tomorrow witnesses will come and testify that there is a mamzer in the family and consequently the children of this family will be considered sofek mamzerim? A possible answer is that concerning the Ran on which the leniency of the Rema is based, he could be talking about a case where it is not clear that a member of the family is actually a mamzer – but merely that there is a rumor. Perhaps it is only such a case where the Ran is saying that there is no need to reveal this information except to modest people [who won’t spread the information]. However when two witness know for certain that a mamzer assimilated into this family it is very difficult to claim that they should not testify since the children of this family – once the information becomes public that there is a mamzer who is mixed into this famly –will henceforth be sofek mamzerim.
