While all major speaking roles have now been cast, a number of non-speaking extras or “featured extras” (as GRRM termed them) still seem a bit nebulous. It appears one of these has been filled today, however. According to a tweet from BreakParrGolf, his daughter Aimee has been cast in the role of Myrcella. Following his website link, it seems that the young lady that slaps him around a bit in his promotional golfing video is his daughter. The 2 minute mark gives the clearest picture of her.