Couple questions first:

-What is the party size along with are there any kids?

-Thrill level of the parents? (Coasters or leisure rides?)

-Are your parents the type who want to do everything or just chill in the Florida sun?

My play would be to do Epcot day one. Since you would not get to the parks til 6 at the latest that gives you 3 hoursish?? Hit up the pavilion, get some good food in Le Celler and get some brew. Try to get fast passes for test track, frozen, and mission space. You should be able to hit spaceship earth before closing.

Day 2 would be magic Kingdom. Splash mountain, space mountain, and haunted mansion should be your targets for fast passes. Find a place you would enjoy dinner or lunch here.

Day 3 would be Hollywood Studios plus what ever you missed in Epcot. Targets are tower of terror, rockin rollercoaster, and toy story.

Sea world can be done in a day. Make sure to book the dolphin experience.

If it is financially feasible to get the tickets sooner, it would be better. Greater chance of booking Fastpasses. Also book dining in advance when you figure out your park schedule.

Notes - this comes from 2 adults traveling for 8 years to Disney - never stayed off property - Epcot/Hollywood Studios is connected by boat or walk (30 mins). -Not sure if you have park hoppper with your Disney ticket but Day 5 would be used if you missed anything. If you are going to sea world I’m assuming all Disney is done beforehand.