If a woman remarried under the assumption her first husband was killed, and someone finds out many years later that her first husband was in fact still alive when she remarried, is he obligated (or allowed) to let her children (born from her second husband while the first was still living) know they are mamzeirim?
By not telling them he is allowing the creation of more mamzeirim when these children and grandchildren (indefinitely) marry. On the other hand, perhaps by not telling (and know one knows) they do not carry the halachic status of mamzeirim?