SO my most obvious connection to yours would be Margaret and Calla, as Calla is not only a teacher at the high school, but she's the English teacher, so her classes are probably frequently making their way to the library. Then I also have Finn and Josie, who are both high school students; the latter is pretty well behaved, but I feel like Finn has probably been a pain in the butt before. He is frequently late returning his books.
As for Violet, Calla goes to the farmer's market as often as she can and probably sees Violet there and buy flowers pretty frequently. Same with Rowena, because she likes to spend her money locally as much as possible, and also takes pictures of the stands and stuff while she's there. So they might at least know her in passing. :)