Harriet's parents say they "want to get to know her" now that Ole Golly is gone. Also a Tear Jerker in that they had no role in her upbringing before.
After Harriet's Extreme Mêlée Revenge that follows her parents confiscating her notebook, they finally get the memo that taking it away wasn't a good idea.
At night when said Melee plays out, which inconvenienced Harriet's mom who is a Trophy Wife, her mom still tucks her into bed when she falls asleep in her day clothes.
The child psychologist who examines Harriet makes note that she is brilliant, which is nice to notice since Harriet's Brutal Honesty makes her hard to like.
Harriet's mom offscreen calls Ole Golly to write a letter to Harriet, asking for a story and offering advice on how to handle the notebook situation.
They also arrange some Screw the Rules, I Have Money! to make Harriet junior editor of the school newspaper, so that she has a proper outlet and can focus on her work.
Sport and Janie forgiving Harriet at the end after she prints that everything in her notebook was lies.
In The Long Secret, Harriet hangs out with Beth Ellen throughout the summer, and Janie visits for a weekend. She also mentions Sport as a friend. Whatever damage the events of Harriet the Spy had caused have been repaired. Even though Harriet continues to write in her notebook, nobody even brings up any of the issues of the previous book.
In The Long Secret, Harriet is shown to be closer to her parents, even having a spiritual discussion with her father. Her mom is seen as a more loving and encouraging influence compared to Beth Ellen's mother, who lives as a traveling lady of leisure who neglects her daughter, expects Beth Ellen to have Acceptable Feminine Goals, and throws a fit when Beth Ellen says she wants to go to college and pursue a career as an artist, naming Harriet's mother (who is married to her ex-boyfriend) as a bad influence on her and Harriet. It's somehow nice to see Mrs. Welsch as more than a clueless Trophy Wife.
Also Beth Ellen, despite her grandmother being old-fashioned and playing cards and leaving her with a nanny who diets a lot, would rather live with her grandmother than with her mother.
There is a scene that pre-dates Are You There God? It's Me, Margaret. where Beth Ellen gets her first period and both Janie and Harriet comfort her by saying every woman gets it, even Marie Curie, their hero, and a) there is nothing wrong with her and b) far from the "welcome to the wonderful world of womanhood" jazz that was in so much literature for girls on this subject at that time, Janie flat-out hates it and declares her intention to find a cure. She also disabuses Beth Ellen of some myths she's picked up about it from her grandmother. Real solid messaging for a YA book in the 1960s.
1996 movie
When Ole Golly and Harriet reunite.
The Boy With the Purple Socks speaking up and nominating Harriet to be the new editor of the school newspaper.
2010 movie only
Beth standing up for Harriet and voting for her blog.
