Upgrading 1 day "two park" passes

[Belle5]

If we are REALLLLY enjoying ourselves during our one day at USF/IOA and we decide we need to give up another one of our WDW days and come back...can we upgrade our tickets to a two-day, two-park ticket ---toward the end of our first day?

The reason I hesitate to do this from the beginning is that we are not coaster people and it will be too cold for water rides.

 

[Metro West]

If we are REALLLLY enjoying ourselves during our one day at USF/IOA and we decide we need to give up another one of our WDW days and come back...can we upgrade our tickets to a two-day, two-park ticket ---toward the end of our first day?

The reason I hesitate to do this from the beginning is that we are not coaster people and it will be too cold for water rides.

Yes...just stop by Guest Services at either park and upgrade there.