Thanks @m4lvin for your reply.
So maybe I will just give it a try without resizing stuff in advance. (of course I will still take backups 
)
Can you have a short look to this thread: Encryption password does not work anymore for normal boot but for twrp (changed with snooperstopper)
I (as well as @freibadschwimmer ) ran into a problem while using Snooperstopper and Iām afraid that this will happen again. Not sure if this is a specific problem while resetting encryption password with Snooperstopper.
Eventually encryption password should only be set and changed via encryption menu of the OS. Snooperstopper should only be used to set a separate screen unlock password/pattern. Just a theory.