Fionnula Flanagan found resonance with her character in "Divine Secrets of the Ya-Ya Sisterhood."

ATLANTA, Georgia (CNN) -- Fionnula Flanagan knows a Ya-Ya when she sees one -- and she sees several in "Gone with the Wind."

She and her "Divine Secrets of the Ya-Ya Sisterhood" co-star Shirley Knight received a tour of Atlanta's Margaret Mitchell House, a repository of the "GWTW" author's memorabilia, hours before the Atlanta premiere of their new movie.

"I think all those women -- Margaret, Scarlett [O'Hara], Melanie [Hamilton] -- were all Ya-Yas ... all those fabulous women who knew how to run society," Flanagan says exuberantly.

It wouldn't be the first time the Ya-Yas and "Gone with the Wind" have crossed paths. In the film, the younger Ya-Yas also travel to Atlanta for the film premiere of "Gone with the Wind," based on Mitchell's book.

Flanagan and Knight join with Maggie Smith and Ellen Burstyn to make up the Ya-Ya Sisterhood, a group of lifelong friends from a Louisiana town. They come together to help Burstyn's character, Vivi, reconcile with her daughter, Sidda, who is played by Sandra Bullock.

Becoming Ya-Yas

In real life, Flanagan and Knight appear much as their characters. Knight, who thoughtfully answers questions, is dressed casually in a dark-blue suit. She plays Necie, whom she calls "the nice one, the quiet one."

Flanagan is her opposite, both in look and personality. She wears a crisp, high-collared white shirt with a wildly colored beaded necklace and roars her quick-witted responses. In the film, Flanagan is Teensy, a wisecracking recovering alcoholic with whom Flanagan closely identified.

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"That resonated very much with me, because my tribe is full of alcoholics, many of whom didn't get sober," she says. "I was fortunate that I did many years ago."

For a summer film, subjects like alcoholism, mental illness and drug abuse -- all a part of "Ya-Ya Sisterhood" -- may seem like heavy fare. But both actresses say that the "Ya-Yas'" struggles will strike a chord with moviegoers.

"Everyone has someone in their family who has a drinking problem. I think that's inevitable. Everybody quarrels in a family, and they don't speak to each other for months or years. It's usually always over some little thing," Knight says. "But it really isn't about some little thing, it's about something much deeper."

Confronting ageism

"Ya-Ya Sisterhood" is also exceptional for a summer film when it comes to its cast. Burstyn, Smith, Knight and Flanagan are all distinguished actresses of the stage, film and television. They're also all middle-aged.

Flanagan and Knight concede that making a movie featuring mature actresses in an industry obsessed with youth can be a deterrent to getting a movie green-lighted.

Shirley Knight: "Men are allowed to get older and women are not."

"Men are allowed to get older and women are not," says Knight. "It's just not allowed."

"There are plenty of roles for older women. They just don't happen to be the roles that normally carry the picture. For older men, that's not so," says Flanagan matter-of-factly. "[This movie] may change that, and I hope it does. But you know, it's merely a reflection of what society is ... Hollywood merely reflects the ageism in society."

Flanagan, Knight, Smith and Burstyn are only one group of Ya-Yas in the movie. There are also actresses who play the Ya-Yas as children, and a third group -- including Ashley Judd -- which plays them as young women.

Knight and Flanagan say working on the film -- particularly with their younger counterparts -- was a pleasure.

"We had a wild night out with them in Wilmington (North Carolina, where filming took place)," says Flanagan.

And what happened? Neither will say. After all, they're not giving away all the film's -- or the filming's -- "secrets."

"That's for another time," says Flanagan.