What is the ruling if the second husband marries her while she or he knew of the existing reconciliation?
General Chapter
Al-Mughni
Book of Reconciliation (Return During 'Iddah)
Primary text
If she married him with her knowledge of the reconciliation, or if either party knew, the marriage is void without disagreement. The intercourse is forbidden for the one who knew, and the ruling is that of an adulterer regarding the prescribed punishment (Hadd) and other rulings, because he engaged in intercourse with another man's wife while having knowledge.
Supporting text
If the claimant of reconciliation has no proof, and one party denies it, his statement is not accepted. However, if both deny it, the marriage is considered valid in their regard. If both confess to the reconciliation, it is established, and the ruling is the same as if evidence had been presented.