I try to keep my smugness playful. Obviously, I’m not advocating drinking to blot out the days when life is hard, but I hate the way Megan makes me feel, like she’s always looking down on me. I’m telling you, if she isn’t her school year’s bully, I’ll eat my breakfast (which I still can hardly look at right now).
This isn't adding up. Generally the psychology behind bullying is extremely severe inferiority complex or perhaps the victim of a bigger bully. But this younger sister comes from a very loving kind family. So her and the twin brothers narkiness towards Emmy doesn't fit the situation.
Even if they are copping some flack from other kids at school for having a sister that's a TV celebrity. Seems that would realistically make them more popular to get closer to the star, then what the author is presenting to us right now.

