I know that this discussion went on for a while, but it seemed to me that nobody could find some "real" reporting on the subject of Marjorie Gross' passing. Well, here's some "real" stuff--from the 12-22-96 Encore section of the Sacramento Bee, where they list the deaths of people in the entertainment industry:
MARJORIE GROSS, 40, writer and producer of the TV series "Seinfeld."
Not a whole lot more mentioned. You might want to check People Magazine, they'll probably say a bit more than this.