I noticed that this e-mail thread is from 3 years ago. However, Southwest has done nothing to make it easy to add a wheelchair to an existing reservation. Southwest.com is one of the worst designed websites for an airline of their size; this should be especially embarrassing for a company that only sells directly and thus really depends on its website.

I think I have figured this out--FINALLY--after repeated prior efforts and after many experiences calling them (with long waits). It still took a half hour plus to do so since this feature appears to be a closely guarded secret.

Here is how you can add a wheelchair to an existing reservation:

1. On the homepage ... click on FLIGHT/HOTEL/CAR (on top right).
2. In box that appears, under column saying FLIGHT ... click on "Manage Reservations"
3. On "View/Share Itinerary" page input confirmation #, name ... and click the CONTINUE button.
4. Will land you on page that allows you to "Add/Edit" ... under Disability Options

This should work ... UNTIL Southwest decides this process is too easy and buries it again on the next site update--which happens frequently.