Hi Ken, welcome to planDisney!
Great choice on opting for the
park hopper tickets and the
Genie+ add-on. Both are MUSTS for me whenever I go to visit the Disneyland Resort. Park hopper gives you ultimate flexibility, allowing you to truly create the perfect day, and Genie+ is a no-brainer! I have two little kiddos, and any time savings I can get from having to wait in line is priceless!
Back to your main question, you can absolutely upgrade your current 3-day park hopper tickets to 4-day park hopper tickets! But unfortunately, you cannot do this online. The easiest way to do this is by visiting the Disneyland Resort Main Entrance Ticket Booths, but that might be a bit difficult for you since you're not local. I recommend calling the
Disneyland Resort Ticket Line at 714-781-4636, and the amazing Cast Members should be able to help!
And the good news is that I checked the
Theme Park Reservation Availability Calendar and there is still full availability at both parks for the month of November 2022 for park hopper tickets, so you should be good to go!
See ya real soon!
Jin