Can you post a video of said transformation? I've only ever seen bits and pieces of the show and don't recall seeing a dress change.
(I do recall discussion on here a couple years back about a Cinderella dress change in a show in Tokyo that may also have played in Florida)
If you're referring to the "Make it blue"/"Make it pink" Aurora dress in Castle Couture, I believe it's just a white dress that they have strategically lit with either blue or pink lighting.