Is the white silk scarf "the phantom's" only link with reality?

In her last adventure, Mandie and her best friend have discovered a mysterious old trunk in the attic of their boarding school. A set of old letters includes so

This boxed set of Books 6-10 of the Mandie Series includes these titles: Mandie and the Medicine Man, Mandie and the Charleston Phantom, Mandie and the Abandone

Someone is going through Mandie's and Celia's rooms and Mandie's graduation dress is missing.

“When we learn to stop wasting our precious energy on what we can’t control, we can begin to discover the power of losing control.” At the age of eighteen