Changing only some family members on FPP

ok - i goofed slightly. on nov 26 i booked A&E for whole family. Meant to book for DD and me and then book DH & DS on space mountain. how can i change just DH&DS on our FPP?

When you log in, and select Modify FastPass, then choose your date, you’re given a page showing your party’s existing FastPasses. Choose a new time, and then uncheck those guests who you don’t want to change: