 In 1989, sisters and television presenters Gayle and Gillian Blakeney were cast as twins Christina and Caroline Alessi respectively, after they wrote to the show's producers at Grundy about making an appearance.They started filming their first scenes seven months after signing with the show.The Blakeneys had an interest in twin psychology at the time, and they worked with the scriptwriters to make sure their characters were portrayed as authenticate as possible.