Stepsister Swappers.

Hot Pearl and Milka Way have been best friends for years. They helped each other through rough times when their parents got divorced and shared horror stories about having to get used to living with stepbrothers. All grown up, they have gotten used to their new step-siblings and have even started dating one another's once-annoying step-brothers. They get to do everything with each other while still dating. It is the perfect situation. The guys are quite athletic and suggest a double date of playing badminton.