Scenario:
I fly somewhere with a friend as my companion.
From that location I then fly somewhere else but need to designate a different companion for the next flight.

Would the best approach to this be to buy both tickets and then add Companion 1 to the first leg. Then as soon as the first leg is completed call SW and change to Companion 2, then logon to the website and add Companion 2 to the second ticket? Any issues with adding companions only a day or two before the flight? Can it be done as long as there is space available?