Well UTactor, welcome to the boards. If you truly were an extra, that is very cool. Could you yet us know what scene you were in and if you were seen in the movie when it was released October 20th? How did you become an extra?
I'm a little confused by what you were saying though. You kind of repeated the same info multiple times, and changed it a little each time. Isn't Marnie the oldest sister, and I believe the oldest of the 3 children? There was the younger brother who is also in it, and the youngest sister, who I don't know if she is in it or not. I think it is just a new actress, the girl from the "Gilmore Girls," I forgot her real name but she is pretty big, is playing the Marnie character, not the girl who was in the last three and in the other Disney Channel Original Movie, "Quints."