Actress Christie Burke is rumored to play teenage Renesemee in Breaking Dawn. This has not yet been confirmed by Summit Entertainment, but we will keep you updated. I have added spoilers (under a spoiler cut) below regarding the scenes the actress who will play teenage Renesmee Cullen will star in.
Spoilers Below thanks to NessieMackenzie & TwiCrackAddict:
P.S. I threw this comparison together quickly and have to say, YES! Amazing fit!!