BTIZ wrote:

My remarks : The agreement of ACTING PIC and ACTUAL PIC should be made in
advance between the two pilots...

There is no such thing as ACTING and ACTUAL PIC.

There is exacting person who is pilot in command.

What you are confusing is that the a person who is NOT pilot in command
can log pilot in command time if they are the sole manipulator of the
controls of an aircraft for which they are rated.