From a Squared Set.
  
  Heads move into the middle; 
  Right Arm Turn 1/2;
  Head Boy Left Arm Turn 3/4 as
    Side Girl Veer Right (to hook onto Head Boy) as
    Side Boy Courtesy Turn Head Girl;
  all Promenade 1/2 to end in a Squared Set.

  Repeat the above once more (i.e., Heads move into the middle...)
  Then repeat the above two more times, replacing Heads with Sides and vice-versa.