Eugenides has said that one of the things that he remembered about the suburb where he grew up was that everyone knew everyone and was willing to lend a hand. With the Lisbons, a bunch of people try at first to help, but under the horrible circumstances, no one knows exactly what to do. The neighborhood men come by to help clean up the house as it deteriorates, but they have no contact with the family. Eventually, people leave the family alone, not knowing what to say. There's a whole parade of Neighborhood Parents who just speak in clichés and try not to let the Lisbons' sorrow infect their own happy homes.
The Catholic priest, Father Moody, tries to counsel the Lisbons but is at a loss. He tries to be forgiving, and lists the suicides as "accidents" in the church records so the girls aren't considered to have committed a mortal sin in the eyes of the Catholic Church. Dr. Hornicker, the psychiatrist, recommends that the Lisbons relax their rules but can't explain to himself why Cecilia killed herself or why her sisters followed suit. Linda Perl is a reporter whose simplistic explanations for the suicides don't satisfy anyone.
Mr. Lisbon's boss, Mr. Woodhouse, ends up sending him on a "leave of absence" (aka fires him), while his wife, Mrs. Woodhouse, has the bright idea to plan a "Day of Grieving" at the school but doesn't really have the expertise to actually deal with it. Old Mrs. Karafilis is an immigrant grandmother who probably understands a lot about tragedy but can't speak English, so we don't get her perspective.
Uncle Tucker must be somebody's uncle, though we're not sure whose; one of the narrators. He lives in the garage across the street from the Lisbon house, so he has a great view of the family and lots of interesting theories on the girls.