Hello there Spiros,
Welcome to planDisney and thank you so much for your question! My wife and I had a chance to visit your beautiful country last year to celebrate our anniversary and had such a wonderful time exploring Athens and Santorini. I'm so glad to hear that you're headed to sunny California for a trip to the Disneyland Resort!
Typically, to change your
theme park reservations for existing standard theme park tickets, you would want to visit the
My Plans hub, which walks you through the steps. However, I have heard from some international Guests that certain sections of the Disneyland Resort website may not be available to them due to local rules and regulations.
As of the time that I am answering your question, I'm looking on the
Theme Park Reservation Availability Calendar and see that July 7th and July 8th have reservations available for both parks, so we're all set there.
Therefore at this point, I would recommend that you
contact a Cast Member at the Tickets line by calling +1 (714) 781-4636. They should be able to see the specific details of your situation and give you a recommendation on your next steps. Alternatively, if you booked this vacation through a local travel agent then you could also reach out directly to them.
Thank you again for your question, Spiros! I hope you have a wonderful visit to the Happiest Place on Earth next week.
Have a Magical Day,
Greg