Is it permissible for a father or brother to prevent his divorced daughter or sister from marrying her former husband, if that is her desire?

It is advisable to exercise caution and not rush into approving the husband's return. One should ascertain that his condition has changed and that his marital conduct can improve. This can be determined by consulting trustworthy individuals. If it becomes clear that reconciliation is the more appropriate path and the wife desires it, her guardian is not permitted to prevent her from returning to him, based on the Almighty's saying: "And when you divorce women and they have fulfilled their term, do not prevent them from remarrying their [former] husbands if they agree among themselves on an honorable basis." (Quran 2:232). Efforts to persuade the father should continue, seeking assistance from close relatives. If he remains unyielding, the matter can be escalated to the competent authority. The husband is religiously obligated to treat his wife kindly, as stated by the Almighty: "And live with them in kindness" (Quran 4:19). If he cannot maintain the marriage with kindness, he should separate with grace. It is not permissible for the husband's mother or anyone else to interfere between the spouses in a way that spoils their relationship. The husband must verify anything reported to him about his wife, as the Almighty said: "O you who have believed, if there comes to you a disobedient one with information, investigate, lest you harm a people out of ignorance and become, over what you have done, regretful." (Quran 49:6).