Yes, absolutely. As long as that adult is listed on a resort reservation, they can access DME and do not need to give Disney flight info prior to arrival. The guest simply needs to go to the ME area at MCO and they will put them on a bus to their resort. You also don't need to have the yellow ME luggage tags to have Disney retrieve your luggage. You can give a Magical Express CM your baggage claim tickets, they will scan them and retrieve your luggage for you. It's well-organized so even those who make last minute travel plans can access the ME service.