Sonja's Sister

Sonja's Sister was the sister of Sonja and the woman Gary Heffley wanted to date. One day, Gary took Sonja to a baseball game and planned of breaking up with her so he could date her sister instead. But just then, an airplane flew up with the banner "Marry Me Sonja?", it was supposed to be for another Sonja but Sonja thought it was for her and agreed. Gary's best man Leonard said this, after this Sonja knew she was cheated so she probably divorced Gary and the marriage ended before they could even get to the honeymoon.