I am trying to identify several books (I believe it was a series) about the day-to-day lives of two families. I read these books as an elementary school student in the early 2000s.
As I recall, the two families each had three (it may have been two?) children. One family had only sons, and the other family had only daughters. The two families were neighbors on a cul-de-sac, or otherwise lived near each other. The book was set in the second half of the 20th century. I recall there being a swinging footbridge or other trail connecting the backyards of the two houses.
Obligatory Children's Novel With Bridge Disclaimer: I am certain the book is not Bridge to Terabithia
I believe there being several books. I remember one where the three sisters climbed onto the roof of the brothers' house when the brothers were home alone. The sisters then began making shrieks and "oooo's", pretending to be ghosts to scare the brothers. I recall that this scene, of the girls making noises on the roof while the brothers were scared inside, being depicted on the cover of the book.