Did you call Delta? They should be able to tell you.
Usually (and this isn't international flights, so it may be different) when my hubby goes to the airport to pick up his 10 yo daughter for her visits, he goes to the airline desk. They check his ID then give him a pass and take him back through the gate so he can get her right off the plane. (He doesn't go on the plane, but waits right at disembarking point.)
I assume it will be very similar for you (i.e. you'll go through customs with her), but I'd call the airline just to be sure. If they can't help you, ask them who can. They should be able to give you numbers to call.