In the player's guide it mentions
"You’ll have opportunities to
take on passengers for payments several times during
the Jade Regent Adventure Path—your GM will inform
you when such opportunities arise."
Does this ever actually happen in the AP? I don't remember coming across any instances of this actually occurring in the books.
There's a random caravan encounter in module two where you rescue some folks who'd been attacked, but I think that's about the closest it comes to it. The Player's Guide also said there would be opportunities to change relationship type (enmity to friendship and vice versa) and I don't remember that occuring either. Must have just been something that got missed.
Changing relationship type comes into play in the players guide, where it says that if you enter a romantic relationship with one of the NPCs, you change from enmity to friendship without any penalties to the relationship score.
If you got an enmity relationship with someone, and then always help them however, the GM might rule it switched to friendly now.
I don't really think there can be any hardcoded points in the AP were you can switch this, since its so much dependent on the actual relationship dynamic itself.