When my mother died, I called Delta to cancel my wife's flight and they gave credit in amount of ticket minus $200 change fee and put notes in record that she was due the $200 due to death in family. No issues when I went to book her a ticket using the credit getting full value. Just a couple of questions from DL on phone was all I had to do.

It doesn't need to be a death only; DL also follows similar rules for grave illness (I had cancelled my trip due to downturn in my mother); just provided info such as name; hospice name, and location.

Marc