I see, thank you for that information!

So the files on machine B are owned by userB, and if he and userA happen to be administrators, userA can transfer file ownership to userB, who he is impersonating.
But what is the difference between an authenticated logon through a limited user account and an authenticated logon through an administrator's account? How can I make the taking over of file ownership work not only for administrators, but also for limited user accounts? After all, userA is impersonating userB, and userB does have the rights to take over file ownership!