Originally Posted by
dlinsider
Changing your outbound fare means that your whole ticket has to be recalculated like you are buying that ticket today.The T fare available in that market today may be more expensive than the T fare you purchased back when you bought your ticket.Also if T is not available now regardless if you are holding a T fare on the return that fare will be recalculated to what is available.
Thanks for a perfect answer... someone else bought me the ticket, should have upgraded it right then!