Determined to be a good big sister, Rex starts spending all her time with the baby her family has adopted, making her neighbor Pinky fear that he has lost her friendship.
When Rex accompanies Pinky and his relatives on their traditional trip to pick and carve pumpkins, she feels left out because of the jealous behavior of Pinky's cousin Abby.
Rex and her best friend Pinky decide that they like each other enough to get married, and all their stuffed toys and dinosaurs appear as guests at the wedding.
Rex and her best friend Pinky are upset to learn that their friend and neighbor Mrs. Morgan is moving, and it looks like a family with an obnoxious boy named Ollie is set to move in.