Is it fanfiction if it's written by the original author of the series?

From the WSJ:

When Alloy Entertainment fired L.J. Smith from the popular young-adult book series "The Vampire Diaries" and replaced her with a ghostwriter three years ago, a civil war broke out among fans. One camp swore fealty to the characters and embraced the new books, which still feature Ms. Smith's name prominently on the cover as the series' creator. The other, more vocal faction sided with Ms. Smith and boycotted the ghostwritten novels.

"I would not read those books if they were the last books on earth," said Christina Crowley, a 35-year-old substitute teacher in Riverview, Mich., and a staunch L.J. Smith fan. "I didn't want to read her characters written by someone else."

Now, in one of the stranger comebacks in literary history, Ms. Smith is independently resurrecting her stories about the adolescent undead. She's publishing her own version of "The Vampire Diaries" digitally on Amazon, as fan fiction, creating a parallel fictional universe that many hard-core fans regard as more legitimate than the official canon.

The article then goes into an explanation and discussion of the Kindle Worlds program, but NEVER FEAR, it gets back to the L.J. Smith stuff towards the end. THE WHOLE THING IS FASCINATING. 

(It doesn't, however, explain what the deal is with the last Night World book, which was due out over a decade ago. I knew NOTHING about that situation until recently, when basic research for a seemingly simple reference question sent me down the RABBIT HOLE OF INTERNET DRAMZ. Good times.)