Stacy collides with her exact double, the Duchess
Stacy runs into Lady Margaret, the Prince's camera-shy fiancee, who looks just like her and invites her to a secret palace consultation.

Margaret Delacourt in 3 The Princess Switch films, every moment in release order.
44 moments · 1h 42m · by Favseen
Moments 1–30 of 44
Stacy runs into Lady Margaret, the Prince's camera-shy fiancee, who looks just like her and invites her to a secret palace consultation.
At the palace Margaret explains her arranged marriage to Edward and asks Stacy to trade lives for two days, sealing it with a ballet sponsorship.
To a Christmas love song the two women swap hair, clothes and accents, ending with Margaret's over-the-top American greeting.
Margaret flusters through a stilted chat with Edward, inventing a lazy eye and a royal log, while her double hides behind the couch.
Margaret, now posing as Stacy, cannot keep track of the apron story or explain her new haircut to a puzzled Kevin.
Stacy calls Margaret to report Edward's return; Olivia has already figured out the swap, and Margaret refuses to come back early.
After painting ornaments with Margaret, posing as Stacy, Kevin insists they are just friends, and Olivia gives Santa a heartfelt wish list.
In the toy store, Olivia and Margaret, posing as Stacy, scramble to keep Kevin from spotting the royal couple, then an old man needs a push.
Kevin gives Margaret, still posing as Stacy, a gift and tells her he feels more than friendship; after a kiss she asks him to forget it.
Stacy and Margaret meet to trade back and realise each has fallen for the other's man.
The winner is announced, and Stacy, dreading presenters Edward and Margaret, tries to skip the stage until Kevin insists.
On stage the look-alikes come face to face; backstage Margaret explains the switch and declares her love for Kevin, and Edward his for Stacy.
Olivia hails Stacy as a real princess, the bouquet is tossed, and Kevin and Margaret make New Year's plans.
Olivia engineers kitchen time; Margaret clearly has never seen her own kitchen, a flour fight breaks out, and Antonio walks in.
Margaret is announced, Antonio flatters her, and Kevin finally cuts in; they agree to go back to being spontaneous, as friends.
Margaret's party-girl cousin makes an entrance, takes selfies, flirts with Kevin and gawks at her look-alike Stacy.
Antonio pulls Margaret away from Kevin on a false emergency, gives her a gift and asks her to consider being more than friends.
Olivia's rescue plan for her dad: Stacy stands in as Margaret at the concert so Margaret and Kevin get time alone.
Olivia covers for Stacy while Mindy and Reggie coach Fiona on Margaret's walk and Stacy and Margaret swap clothes and rings.
Olivia steers Edward away from Stacy's room into Christmas shopping while Margaret, dressed as Stacy, and Kevin tour Santa's Magic Village.
Alone at last, Margaret says she will not give up the crown and Kevin fears holding her back, until she tells him it is him she loves.
Margaret, still dressed as Stacy, gushes about Kevin to Fiona posing as Margaret, who turns it into a cheating accusation.
Edward apologises for hovering to the wrong woman; Margaret reveals herself, and a fired Donatelli helps them work out Stacy is missing.
Stacy hides, gives Reggie and Mindy the slip, and Edward and Frank arrive in time; the reunited couple make promises.
Mid-oath, Margaret and Stacy burst in; Fiona blames Antonio, and Margaret gives her first royal command.
Margaret, still dressed as Stacy, chases Kevin to the gate, explains it was Fiona, and Kevin asks her to marry him.
Margaret asks a passing officiant to marry them on the spot; they improvise vows as his flight is called.
On Christmas Day, Margaret takes the oath in full and is crowned to cries of long live the Queen.
Mid-rehearsal, Margaret and Stacy learn the Vatican's relic vanished from a guarded vault: drugged guards, wiped drives, no leads.
Edward's unhelpful Belgravia jewel story, then Stacy pitches a crooked insider and Margaret names her cousin Fiona; Kevin vows to nail things down.