Barely six months old and backed by private equity, ex-William Morris agent Fred Westheimer’s Lone Star Film Group is already carving out its place on Hollywood’s map of financing and production shingles.

Company is co-financing and co-producing “Chaos Theory” with Warner Independent Pictures and Castle Rock Entertainment. Pic, produced by Frederic Golchan and directed by Marcos Siega (“Pretty Persuasion”), is to begin shooting in January.

The company also is co-financing and co-producing the Michael Douglas starrer “King of California,” from “Sideways” producing team Alexander Payne and Michael London. Emmett/Furla Films and Avi Lerner’s Millennium Films also are co-financiers.

As for leading the company’s troops, Westheimer didn’t go the usual route when looking for a production topper — he tapped his 32-year-old daughter.

Erica Westheimer was Laura Linney’s personal assistant when she got the call from her dad, who left WMA in spring after nearly four decades to launch the film financing and production company. Earlier, when just out of college, she was a costume designer, first for theater and then movies.

Part of her initiation into big business: Lone Star, which intends to turn out three to five movies a year, is looking to partner with a studio on a slate of films.

Company, based in Beverly Hills, won’t disclose the identity of its financial backers, and Fred Westheimer isn’t talking. The longtime agent who repped John Travolta and Candice Bergen, was first a TV agent at WMA before moving to the film side, where he was the agency’s head of motion picture talent for six years.

As far as Erica is concerned, she said she’s gotten to know all aspects of development and production, both from her work as a costumer designer and as Linney’s assistant these past two years. (Over the summer summer, she was with Linney on the set of “Jindabyne” in Australia.)

After graduating from design school in Boston, Erica took a job as a publicist, a gig she quickly realized wasn’t for her. Through a friend, she was introduced to Broadway costume designer William Ivey Long, with whom she worked for several years.

She said the pact she and her father have made is simple: Everything begins and ends with what’s on the page. That means that both must agree that a script is worth pursuing.

“Chaos Theory,” originally set up at Warner Bros. Pictures, is an offbeat comedy penned by Daniel Taplitz. Film, starring Ryan Reynolds and Emily Mortimer, is a story about a man who finds out he is sterile and that his daughter was actually fathered by his best friend.

“King of California,” which marks the directing debut of Michael Cahill, is a comedy about a teenage girl with a manic depressive father who is convinced there is buried treasure in the San Fernando Valley.