Suggest books where step siblings are fighting initially but then become one family

[Bookworm]

Suggest books where the romance is low but families are reunited or step siblings get together as family. Initially there would be fights, pranks, mild bullying in school but later they all come together to become one family

[Ann]

From the Babysitters Club series by Ann M. Martin:
Dawn's Wicked Stepsister
Here Come the Bridesmaids!

Same author but not in BSC series: Bummer Summer

[Rachel]

The Animal, the Vegetable, & John D Jones

[Rainbowheart]

The Sisters War
Apple Pie Promises

[Zev]

"Tiffany Sly Lives Here Now" by Dana L Davis might work for this.