There is a page when you go in and view itinerary online that allows you to forward that itinerary to 4 other people. This is after the reservation has been made and is sitting in your MySouthwest area. I think if you send it to someone else, you also get a copy at the same time to the primary e-mail address tied to the account.

my son is coming home this weekend, I believe when I sent his itinerary and his friends itinerary by e-mail to a couple people, I got a copy at the same time, even though I did not request one. may or may not be a similar scenario