Does a divorced woman, who was irrevocably divorced once, have to observe the waiting period (iddah) again if she discovers, after her initial waiting period has ended and her husband has married another woman, that he had taken her back while she was in her family's home without her knowledge?

If a man divorces his wife fewer than three times, he has the right to take her back during her 'iddah (waiting period), even without her knowledge. If the husband takes her back during the 'iddah, it is a valid return, as Allah the Almighty says: (And their husbands have more right to take them back in that [period] if they wish for reconciliation). If he divorces her another time after the return, she must observe a new 'iddah of three menstrual cycles, even if no intercourse occurred, because the return nullifies the first divorce and restores the woman to the marriage. Ascertaining the clearance of the womb is not sufficient for her to exit the 'iddah, as the 'iddah is not limited to ensuring the clearance of the womb; rather, it has other rulings. Therefore, the 'iddah is obligatory for a divorced woman even if the husband has not consummated the marriage with her or has been absent for a long time. Accordingly, you must observe an 'iddah of three menstrual cycles from the time your husband divorced you the second time.