Hello, I had an $8500 flight credit from a Covid cancellation. Expires September 30, 2022. Want to purchase a flight before the expiration date for $1500. For the remaining $7000 that will be issued as a TRIP credit, can I use that multiple times for different flights through to the new expiration date? I.e. is it basically like a running balance that I just need to use up by the expiration date? Want to make sure I don’t have to spend all $7000 at once.