Hiya Darlene - welcome to
planDisney!
Thanks for stopping by with your question for our team of panelists. We love helping Guests just like you plan your very own, very magical, Walt Disney World Resort vacations!
Darlene, if you have the Park Hopper Option added to your Theme Park Ticket, you should have no problem heading to a different park in the evening. That being said, it's always important to remember that Park Hopping is subject to availability and may be restricted if a park reaches attendance capacity on any given day. So, the only way to be certain you can join your family at a
Magic Kingdom Fireworks Dessert Party would be to make a Park Pass Reservation for Magic Kingdom for that day, as is recommended when booking such experiences.
That's the technical answer, but in practice, Park Hopping is very rarely restricted and is usually associated with events or holidays. If I were you, I wouldn't hesitate to make a Park Pass Reservation for EPCOT, enjoy my day there, and then hop over to Magic Kingdom in the evening to enjoy the dessert party. Make sure you save time to experience
TRON Lightcycle / Run Presented by Enterprise - it's Magic Kingdom's newest thrill!
Ryan J.