"Twilight" author Stephenie Meyer took to Facebook on Wednesday night to celebrate -- and to officially announce the addition of Mackenzie Foy to the "Twilight: Breaking Dawn" cast.

The nine-year-old actress will be playing Renesmee Cullen, who is Bella and Edward's half-human/half-vampire daughter in the "Twilight" finale.

The news has been circulating unofficially for a week, but Meyer wanted to reach out to fans directly after reaching a milestone on the social network: more than 15 million people have now signed on as fans of the franchise on Facebook.

"Congratulations to the Twilight Facebook Fan Page! 15 million fans! You guys never cease to amaze me.  In other news... Very excited about our new Renesmee, Mackenzie Foy. She's an amazing young actress and I'm excited to work with her.  I hope everyone had an enjoyable summer!" posted Meyer.

Actors Christian Camargo, Mia Maestro, Casey LaBow, MyAnna Buring and Maggie Grace also joined the production last week. Foy is among the last casting announcements so that shooting may proceed.

The young Foy has appeared briefly on TV shows like "FlashForward."

The first "Breaking Dawn" movie is scheduled for release on Nov. 18, 2011, with the second due a year later.

What do you think of Foy's casting? Does she look like a love-child of Robert Pattinson's Edward and Kristen Stewart's Bella?