FIL/BIL - Mehram or not?

Re: Working Women - the Islamic Perspective

in Islam, a saali can NOT marry her brother in law as long as her sister is married to him…they are meHram to each other…

…however, after the woman has been divorced or has died, her sister is once again becomes eligible to marry the deceased/divorced sister’s husband…after death, they revert back to naa-maHram status.