I'm afraid that the new characters were made for the sake of just having new chars. Especially considering that the 3rd pair (Author/Editor) have little to nothing to do with the first two pairs. The first set of chars were inter-related (even if they the pairing didn't have much cross-interaction, relatively speaking); this new 4th pair is only superficially related to the 3rd pair (Heke's mention) so far. I do hope the mangaka proves me wrong, though.
Call me weird, but I like it when the characters in a series actually have something to do with each, even if it is a slice-of-life series. There's little to no connection between the pairing, so it just feels almost like a disjointed collection of stories at this point. I understand the point and focus of each chapter is on the featured pair, but I'm starting to feel this is being taken to the extreme. At this point, I think it'd be a better idea to just make a series for each pairing. Otherwise, I don't really take well to new characters coming out of the blue in the middle of a series without some build up.
I blame Love Hina's Kanoko for my skepticism about new chars showing up out of nowhere; I find it tends to be because the author ran out of ideas for the current cast and needed a new plot/scenario RIGHT NOW. I also dislike unjustified cast expansion/explosion ever since the cluster that was Nanoha StikerS. Or at least how they handled that.