Bell is the widow of the actor John Mills and the mother of actresses Juliet and Haley Mills.
Her grandson, Crispian Mills, is co-writing the script for "The Winged Boy," which is being directed by Luis Mandocki, the Hollywood Reporter said Monday.
"The Winged Boy" will be a family film about an Irish boy who grows wings and learns to fly, the Reporter said.
The film is scheduled to start shooting in Ireland in the spring.
Couple mistakenly served bag of cash at McDonald's drive-thru
Gal Gadot cast as Wonder Woman for 'Batman vs. Superman'