Also, the family in whose townhouse they are gathering has taken a boarder. He's a young middle-class man starting out in the city. I read up on boarding, but I still don't know much about how he and the family would interact, particularly with a teenage daughter. She's being raised by her fairly lax father, who is not too paranoid about the presence of a young man in their household. Nevertheless, how much social distance would be expected of them? They get along well; would they call each other by their first names? (I'm assuming no, but I thought I'd check!)
Searches: "new year united states nineteenth century," "boarding united states nineteenth century," and variations therein.
Edit: Thanks for the responses so far! To specify, I'm interested in situations where families who needed some extra cash were taking in a boarder or two, not an actual boarding house, which of course has a different dynamic.