Is it forbidden to bury two people in one grave? And is it obligatory to separate them if that becomes impossible for years? And what if it's impossible to distinguish the remains?

If a man and a woman are buried in one grave, this is impermissible, for the default is to bury each deceased person in a separate grave, except out of necessity. Scholars have differed regarding the prohibition or detestability of combining two deceased persons in one grave. The prohibition is stronger if they are a man and a woman, and even stronger if the man is a stranger to her. It is forbidden to bury a deceased person in a grave where another has been buried unless the first deceased has completely disintegrated. However, since the combination has already occurred, the grave should not be exhumed, because the harm of exhumation is greater than the harm of combining them.