The relationships between parents and their children are at the core of The War with Grandpa. After the death of her mother, Sally’s father moves from his home in Florida to live with her and her family. He is unhappy because he’s in physical pain due to a hurt leg, he’s living with the grief of losing his wife, and now he’s come to live with his daughter—but that means taking his grandson’s room. Sally must cope with her son’s and her father’s unhappiness. Sally and Arthur must also navigate the change with their children. They choose to give Peter’s room to Grandpa—the decision was beyond Grandpa’s and Peter’s control.

As parents age, their adult children often become their caretakers while these adult children have children of their own. The resulting conflicts, such as what happens in The War with Grandpa, force parents and children to reassess their relationships and find a way to navigate changing roles. Sally and Arthur want Peter to be more mature in accepting his bedroom change, but Peter needed them to appreciate his feelings. Grandpa Jack needs to feel useful and autonomous since the decision that he’d take Peter’s room was made for him.