Could we resume all this by saying that regardless of the physical film ownership, scan ownership is somehow determined by who paid for it to be done?

Since Person #2 paid for Person#3’s film scan, person #2 assumed it’s was ok to pass it over to -1.

Since Mike paid for Person#2’s film scan, Person#2 did not share it.

I think OT.com shall retract the part about unethical behavior from either -1 or Person#2.

All of this is just an unfortunate misunderstanding of all the party involve IMHO.