in HIghbury, but I doubt that they were among the 2nd and 3rd class people to which the text refers. I would assume that they were people such as the shopkeepers and prosperous yoeman farmers such as Robert Martin. Emma told Harriet earlier that she could do nothing for these people (as she could for the parish poor)so they were beneath her notice (if this is not an exact quote, it is the spirit of what was written). To have to encounter these people socially at the apartment of Mrs and Miss Bater would be "a horror" for Emma. As Austen has written Emma so far, she is surely a product of her time and class, with apparently (note that word please) no ability or interest or inclination to challege the conventional wisdom. And why should she challenge any assumption that makes her "better" than most of the people in HIghbury, or indeed the world outside Highbury. Emma is not a rebel by any stretch of the immagination. And IMO if Harriet were to be found to be the natural daughter of a nobody, a prosperous farmer, or a shopkeeper, I would bet that "friendship" would end immediately.