Upgrading a 4-day Hopper

[CarolynK]

We will probably buy 4-day hoppers for my parents. They are going with us, for 6 days, and my mom's stamina isn't like it used to be. It's really hard to know now how she is going to handle the parks, so I'd rather get only 4 days.
This is my parents' first, and most likely only trip to WDW. Unused days on a hopper will never get used again. Is it possible to pay the difference and get a 5-day Hopper once you get to WDW? Thanks.

 

[Dopey Sharon]

Yes, you can. Have a great time!