Desperate to derail the wedding, Harper and Lily visit Madame Jen’s psychic tent at a street fair to cast a hex, triggering a cosmic surge that binds all four family members: Harper swaps into Anna's body, Anna into Harper's body, Lily into Tess's body, and Tess into Lily's body.
Harper (as Anna) and Lily (as Tess) attempt to orchestrate disastrous encounters to make Eric call off the wedding. The plan works too well: Eric, heartbroken by Anna's sudden coldness, cancels the wedding and prepares to move back to London with Lily. This heartbreak forces Harper and Lily to confront their selfishness; Harper realizes Anna's deep love and sacrifices, while Lily confesses to Tess that her rebellion was driven by fear of replacing her late biological mother.
In a race against time, the four women rush to stop Eric at the airport and crash Ella’s concert showcase. Anna (in Harper's body) performs live with Pink Slip, dedicating an original song to her daughters and Eric. Mutual forgiveness and love trigger the cosmic reversal, returning everyone to their original bodies. The film concludes with an impromptu wedding where Harper and Lily proudly serve as maids of honor.