We all know that Mackenzie Foy is set to portray “Renesmee” in The Twilight Saga: Breaking Dawn, but Foy is almost ten years old, and the character is shown as participating in the world of the “Cullens” from her very birth, if not sooner (from within the womb, in many instances), in the story.
So, most of us have just assumed that there would be several actresses (or, since with infants it’s often hard to tell the difference with gender, actors) which would portray the steps in “Renesmee’s” rapid growth process throughout the story.
However, when Foy was cast, there was a lot of emphasis on the fact that she was “Renesmee,” period, end of sentence.
This was further affirmed by the announcement by Bill Condon (on the Official Twilight Facebook page) the make-up artist from The Curious Case Of Benjamin Button, a lodestar example of an actor’s face being successfully added to a baby’s body, would be joining the crew of Breaking Dawn.
Now, though, there are a great many reports, including one which was sent in by a reader of this page, of auditions being held for “Renesmee” at a younger stage of growth.
This would still make sense when it comes to promoting Mackenzie Foy so heavily. Chances are, that rapid growth the character has will be presented on-screen just as quickly as it happens in the book, and the meat of the character portrayal will take place when she does look a little older as a very large portion of the story is the “Cullens” fight training with the new vampire characters. It’s even possible that there would be some CGI implementation of Foy’s face on the body of another who is cast for the role. At this time, though, it’s all still just speculation.
Source: Twilight Examiner