Is it permissible for me to ask my daughter’s husband to make his divorce from his first wife an irrevocable divorce, for fear that he might take her back after marrying my daughter?

The Hadith prohibits a woman from asking for her sister's divorce to empty what is in her vessel, and this applies even more so to others. A revocably divorced woman is considered like a wife, and her husband may take her back during her 'iddah (waiting period). However, it is permissible not to marry a man until the 'iddah of the first divorced woman has expired.