During the term, when the Mean Girls had their parties they made a point of publicising them. This was to insure people knew they were Not Invited.
The Mean Girls worked hard to make Margaret knew she was not invited. This was a waste of time, for not only wouldn’t she have come, if invited, but was out of town on weekends.
Although it happened every Friday, it took a month for one of the girls to actually notice.
That is, Margaret and her family, driving out of town, not returning until Sunday evening. A bit of investigation proved this was standard.
Margaret was not in town on weekends. That meant she was not available to slights, insults, non-invitations on the weekends. To Not Invite her would have to be during the week, during the school day.
This wasn’t worth the thought because Margaret never even came to the cafeteria for lunch.