Walker, who died in a car crash in November, had filmed the majority of his dramatic and action scenes, but his brothers will help "fill in small gaps left in production."
"The Fast and Furious saga is about family," the statement said. "The characters are connected by the bond of family, and it is how all of us who have worked together for more than thirteen years feel about each other. It certainly defines how we think about our fans.
"Having [Caleb and Cody] on set has made us all feel that Paul is with us too," the filmmakers added.
Fast and Furious 7, which resumed production last month, will hit theaters on April 10, 2015, and "will allow the character of Brian O'Conner to live on and let us celebrate Paul in his most defining role."