0073735963 -
Welcome to Flyertalk!
It is a little bit difficult to explain exactly what is going on with your expiration dates without having your confirmation number and actually looking at your reservation to see how payments were applied.
However, in general, each ticket within a reservation can have its own expiration date depending on how that ticket was paid for.
If the TTF that you used all went on the first passengers ticket, then that ticket would carry forward the 1/2010 expiration date from the original ticket. Then if the second passengers ticket was all on CC it will have a new expiration of 1 year from the purchase date of this new ticket (ie: 6/2010).
Since you are now making a change to the original reservation, its going to apply pax 1's original ticket to pax 1's new ticket . . .and pax 2's original ticket to pax 2's new ticket. The leftover funds from each original ticket will carry the expiration date that ticket had.
So - pax 1's downgrade keeps the 1/2010 expiration, and pax 2's downgrade keeps the 6/2010 expiration.
I'm not sure if that made it more clear, or more confusing . . but I hope that it helps
-SWAVictor