I think you meant MDE: My Disney Experience, not DME: Disney’s Magical Express (airport bus). At first, I was thrown by the thread title and your questions, but then I read Nickysyme’s reply and understood. Common - and easy - mistake!
If you’re making dining reservations you can make them for the whole group, it will want names attached to them, but who actually shows up doesnt matter as long as the total number is correct.