Hey there, Sharon!
A very warm welcome to planDisney! We’re delighted you brought a question our way!
I am so pleased that you have already secured your advanced
Theme Park Reservation. And, you are able to upgrade your One Park Per Day Theme Park
ticket to include the Park Hopper Option, subject to availability. But this is not something you are able to do within the reservation system. This change will have to be made in person at the Disneyland Resort Main Entrance Ticket Booth. First, I recommend checking the
Availability Calendar to confirm the Park Hopper Option is available on the date of your visit. Please note that a Park Hopper ticket allows you to hop to the other theme park starting at 1:00 p.m. You are not required to make an additional theme park reservation to visit the second park or hop back and forth between both parks. But, as always, theme park admission is subject to attendance availability.
If you think of any more questions, send them on over to us here at planDisney!
Tiffanie