https://www.disboards.com/threads/f...al-tier-1-booking-anytime-fps-cl-fps.3538258/
Instructions for Checking Availability
You don't have to Cancel when checking availability, rebooking a new park, or when park hopping. Simply follow the instructions below.
From the app:
~ tap the "+"
~ select guests
~ select date and new park
~ continue beyond any warnings
~ you won't lose anything if just checking availability. After checking, back out of the window and your original FP+ remain.
~ when you confirm a FP+ for the new park, that's when any original FP+ are replaced.
Checking Availability for Same Park - Same Day
From the App
~ from a booked FP, choose "Modify”
*(Note: to check availability of a Tier 1 attraction, you must choose an existing Tier 1 to modify.)
~ scroll through selections to see availability
~ original FP remains intact if a new ride is not chosen
* The system does not show ride availability for time slots that are blocked by original FP Return Windows.