(L-R) Mackenzie Foy, Eliza Faria, Sierra Pitkin, Rachel St Gelais If you've read Breaking Dawn (and you should have!), Renesmee grows up real fast, being all half-vampire, half-human and all. Thus, the producers decide to have a few actresses play her. At least, her body doubles. Mackenzie Foy is still the main actress for Renesmee, though. Here's the scoop. Breaking Dawn's Renesmee will be played by 10-year-old actress Mackenzie Foy. She is Renesmee. However, she will also be played by three other young actresses -- Eliza Faria will play Renesmee at age 5, Rachel St. Gelais will play Renesmee at age 6, and Sierra Pitkin will play the oldest Renesmee -- but not the way you might think. After all, it wouldn't be much fun to watch a character whose face is completely different every time she ages in a flash. So special effects artists that also worked on Avatar, behind the movie are going to superimpose Mackenzie Foy's face on the three other actresses'