Are you going to be on the same reservation? Are both of them in your F&F list? If so, when you link the
DVC reservation to your
MDE, list both of them as guests and it will automatically link to their MDE accounts.
If you are not on the reservation, whoever will be the primary guest can do the same thing - i.e., give your daughter the confirmation number, have her link it to her MDE and link her friend via her MDE F&F list.