Thinking Beth is just a good friend of their father's, the girls invite an attractive woman for dinner, hoping Art will fall for her.

Art panics after reading Allison's diary, which reveals that she's driven by passion in her relationship with heartthrob Steven.

Miffed at Kate for signing them up for a twin-testing project, Allison moves in with Beth, vowing to find her own identity---and to celebrate her birthday without her sister.

Kate challenges shy Allison to enter a dance contest with her, but when Kate sprains an ankle, Allison must go it alone in the finals.

Kate is out of her element in Allison's chemistry lab when she poses as her sister, who cut class to go out with a college guy.

To help Kate adjust to her new school, Allison gives her sister a job on the yearbook, and within a week Kate is running the staff.

Kate risks the wrath of both her sister and her boyfriend when she becomes enamored of a fellow working out in a gym.

Kate's inability to pass her driving test doesn't stop her from taking dad's car---and Allison's driver's license---to a rock concert.