Going to Disney, if all of you will be going to the resort on the same day, the best thing to do is mail or fax a copy of the Magical Express Disney bound reservation information as-is to the other(s).
Going home, everyone must be listed on a written reservation, the latter normally delivered to your room door morning of the day before the day you will take DME back to the airport. So long as the written reservation is for about 3 hours* prior to the earlier(est) of the flights in question you are good to go.
If someone does not have a correct reservation as of the morning of the day before the day s/'he will leave the resort then a correct(ed) reservation should be obtained then and there, before heading for the parks.
*This writer does not recommend having or keeping a DME reservation back to the airport less than 3 hours before flight time. Should one get such a reservation it is strongly recommended to have it amended immediately to be for an earlier time. Earlier reservations than 3 hours, if desired, are always granted upon prompt request.