Elisabeth Shue?
The version of "Somewhere Tomorrow" that I own is a 3-Movie disc that has two others on it, and it includes trivia about "Somewhere Tomorrow" in the cover. One of the things it says is "Watch for an early appearance by 1995 Oscar-nominee Elisabeth Shue as Margie." The credits list Margie as being performed by "Lisa Shue," but I've watched this movie a million times and don't see anyone named Margie in the movie.
What about you guys? My first assumption was that it's Lori's friend she's talking to when she goes back to school, but it isn't.