Hi there, Jennifer!
Thanks so much for stopping by with your great question! I spoke with a Memory Maker Guest Services Cast Member today to verify a couple of things and I'm excited to have been given some great information!
Castle Couture is located in Magic Kingdom Park on the Fantasyland side just as you walk under Cinderella Castle. You'll see it over to your left along with Cinderella's gorgeous fountain.
All Guests are welcome to walk in and have portraits taken at this magical location and you do not need to have visited the
Bibbidi Bobbidi Boutique to do so. There are Princess dresses and accessories for sale at Castle Couture, but they do not supply those items to borrow. You can have your little Princess either wear her own costume or she can have the portraits taken in her Park-touring attire. Either way you do it, they are sure to be completely adorable!
I was also told that Castle Couture can be quite busy, but there is another photo studio location at the Downtown Disney Marketplace near the Bibbidi Bobbidi Boutique there that offers the same service and sometimes they are less busy. Of course, this all depends on how busy the Parks are during your visit.
I'm also happy to tell you that the pictures taken by the PhotoPass photographers at Castle Couture can be added to your Memory Maker!
I sure hope this helps, Jennifer! Please don't hesitate to write back in if we can help with any other questions you have.
Wishing you and your family a Pixie Dusted vacation!
~Jackie