The film features a young grifter -- potentially played by Stewart -- who joins Affleck, a more experienced vet.
"Focus" is written and directed by Glenn Ficarra and John Requa, who together helmed "Crazy, Stupid, Love," the magazine reported. Denise DiNovi will produce.
Stewart next appears in "Breaking Dawn Part 2," which opens Nov. 16, and "On the Road" opening next month.
Celebrity Families of 2014 [PHOTOS]