Hi Whitney,
Welcome to the Disney Parks Moms Panel! How exciting to plan a trip to the Walt Disney World Resort!
My family loves the character experiences as well, especially those at
character meals because we avoid the lines and the characters come directly to our table. In my experience, the characters have signed multiple books or photos. I would caution, however, that some of the characters may have a hard time gripping smaller pens to sign. I am not sure how they would sign the photos on your cell phone, but we always bring large pens for them to use for autograph books.
If the character would need to use a finger when signing the photo on your cell phone, that would be difficult for some of them that wear large gloves. I am not sure, for example, how our friend Mickey Mouse would sign unless your editing feature also works with a stylus pen. The characters could probably grip that. I would also just caution that the signing process needs to be fairly quick because the characters have many guests to visit. You might be more efficient than I would be, but it would take me a few minutes to take the picture then get to the editing feature so that the character could sign.
If I have somehow misunderstood your question, please come back and ask again!
Whitney, the characters have always been gracious when interacting with our girls, so I imagine they will do their best to sign the photo on your cell phone. One item per guest for the characters to sign is reasonable. Since it sounds like you may have many great photo opportunities with characters, I hope you have considered Memory Maker. On our last trip, we had over 200 photos with our Memory Maker.
Sending pixie dust your way hoping that all of your character experiences go well!
Magic, memories and Minnie Mouse hugs,
Donyell