You know what, it'd make perfect sense if Ed Spengler from the validated fanfiction was the son of Elon Spengler due to him being Egon's nephew and Elon is his twin brother.
It's all connected, you see. Elon from The Earth Day Special is obviously the father of Ed from the Freddy Krueger fanfic. The truth is right there, lol.
If we take this to its logical (or illogical) conclusion, the Ghostbusters universe includes characters and settings from:
The Earth Day Special
Back to the Future
Cheers
The Cosby Show
Doogie Howser, M.D.
E.T. the Extra-Terrestrial
The Golden Girls
Married... with Children
Murphy Brown
The Muppets
Looney Toons
Crossovers
Casper
Transformers
Denver Ghostbusters Fanfiction
Friday the 13th
Evil Dead
A Nightmare on Elm Street
Mario Bros (?)
I guess this just goes to show, you can always find something new. Now, taking this advert seriously for a second, Janine is still managing the Ghostbusters' finances in 2019. I can only imagine that her and Slimer are promoting Quickbooks in-universe and relating it to the Ghostbusters due to their popularity.
The Louisiana Ghostbusters, which references a TON of other fanfiction, is referenced twice in the IDW Ghostbusters comics. They go on to explain how that reference occurred within their fanfiction.
DOES ANY OTHER FRANCHISE COUNT FANFICTION AS MUCH AS GHOSTBUSTERS!?! I appreciate it for all the fanfilms that are validated because of this, but man, I don't wanna go through adding all of that. Call it a branch timeline or something. Good for them, they're canon, man...