Yah, Trader is my choice on that point as well. Someplace to be Flying was one of those books that looked like it was fun but not a particularly compelling addition to the series, until it became clear that it was the beginning of a trend in that series rather than an isolated incident.

The Onion Girl was the first one I really, really got annoyed with, because it felt like "look, here's another familiar Newford character! And another!"