Don't Change Your Southwest Companion Until You Do This One Thing

One of the best freebies out there is the Southwest companion pass. To earn the pass, you must collect 110,000 miles in a calendar year OR you needed to sign up for the bonus credit card offer at the beginning of this year.
Either way, if you have the companion pass, congratulations!
You can fly Southwest BOGO for the next year or two depending on how you earned your pass.
Your companion can be anyone, a friend, a sibling, a child, a spouse, a neighbor, anyone. But they have to fly with you on the same flight. You can change your companion three times in a calendar year. 

You have to call Southwest to register your companion. Once they are registered, you can add them online to any flight with you.

Makes sense, but what if you want to change your companion at the last minute? You can do it, but you need to do something first. 

Last week, my son was supposed to fly with me to the East Coast, but last minute, he had to change his plans. I had already bought my daughter a seat on the same flight with points. So my thought was to cancel her flight, add her as my companion and then she could fly FREE. 
It took about 30 minutes to get through to a Southwest operator who was happy to make the change, cancel my daughter's ticket and rebook the companion ticket for her.
She checked first to make sure there were enough empty seats on the plane so we didn't get shut out while making the change. No worries.

What we didn't expect, however, is that the computer went bonkers over my flight booked in August now that my son was no longer my companion. In fact, the computer has cancelled his flight three times in August because it thinks he is double booked. 

I had to call Southwest back to get help fixing the error, canceling my daughter's flight and rebook my son's flight for that trip.

Lesson learned. Before changing companions, cancel any future tickets issued for that companion. It just makes things easier.