I'm off to the library.
I tried Terry Pratchett, but I can't get through it. Too many characters, too confusing. I suppose I should have a look again, just for the sake of the POV.
I just finished reading
The Brethren by John Grisham, and he does this in one and the same dialog, against all rules.

The POV shifts from Wes (FBI) to Jan (secretary) and back again.
Wes (FBI) comes in to talk to Jan. She says her boss is busy. He thinks: hahaha, what a blatant lie.
He insists that he must talk to him, and tells her - "almost in tears" - that his wife was killed in a car accident. Jan wished she had coffee.
He says that friends recommended this lawyer.
Lousy friends, she thinks.
At this point the POV lies with her, until Wes says something "to help her".
I thought he pulled this off very well, it was not disturbing at all. It really shows the game Wes and Jan are playing (they're both lying). So maybe that's the reason that you could do it in this dialog, and not in another. But then again, not only the characters, but even the narrator is lying because Wes really didn't want "to help her".
That's the narrator's challenge, I suppose. He/she has to decide what to reveal at what time.