Can you upgrade/add onto AAvacations tickets?

[KrisTX]

AAvacations has a decent package right now offering several hundred dollars of savings with the airfare versus buying it all in parts. BUT the package does not allow me to do 5 days only 4 since that is the number of nights. Strange. We are arriving early on the 1st day and leaving late on the 5th day and really need the 5 day tickets. Can we go to the ttc upon arrival and add an extra day at the 5 day rate? I know I can buy another day at full fare, but it would not be $mart.

Thank you!