Once you designate your companion, they are NOT automatically added to your flights; you still must take steps each time you want your companion to fly with you. Note that you do not have to add the companion immediately. As long as there is at least one seat on the flight (in any class) the companion can be added up until the day of the flight.
Log in to southwest.com and click on “My Account”
Scroll down to “My Trips”
Click on the trip for which you want to add the companion.
Click “Add Companion”
Once you click on that, your companion’s name should pop up as the designated companion.
Scroll down and click “Checkout” or “Continue”
Complete the items with red *, as you normally would, and fill in payment details.
Thank you for your purchase. Enjoy your flight.