Reni is not from Edinmire. Reni is from the capitol. It hasn't been said how long she's been in Edinmire, but maybe she's picked up some local knowledge. In any case, we can assume someone is around that got them going in the right direction, assuming whoever is flying towards Group B is from group A, or some allies coming to help.
Thinking about locals they've encountered, I suddenly remembered Apothecary Guy. Wonder whatever happened to him. I guess some characters just get lost.
{Debates starting a "Where in the World is Carver" thread, complete with artwork illustrating humorous and painful places he could be.}
...Okay, now my mind is wandering too far. Sorry.