To add a Park Hopper option to an existing Disney reservation in 2026, the most efficient method is through the official My Disney Experience (for Florida) or Disneyland (for California) mobile app. Log in, navigate to the "Tickets and Passes" section, and select the specific ticket you wish to modify. You should see an option to "Change Ticket," which allows you to add the Park Hopper feature. You will be required to pay the price difference between your base ticket and the Park Hopper—note that this fee is a flat rate for the entire length of the ticket, so you cannot add it for just one day of a multi-day pass. Alternatively, you can visit any Guest Relations window or ticket booth at the theme park entrances, or call the Disney Ticket Line. If your ticket was part of a "Vacation Package" booked through a travel agent, you may need to contact them to make the adjustment. Once added, you can "hop" to any other park starting at 11:00 AM daily, provided you have already scanned into your first "reserved" park of the day.