Heigl's Wedding Advice for Simpson, Clarkson

Katherine Heigl's upcoming film The Big Wedding is all about the events surrounding one couple's big day, which caused her to reflect on her own wedding years ago. Gauging her own big day, she gave her advice for soon-to-be celebrity brides Jessica Simpson and Kelly Clarkson.

"I was really particular about my own wedding 'cause I wanted to avoid all that kind of drama," said Heigl, who was married in December 2007. "I just felt like the smaller, more intimate group, the better 'cause the bigger...it gets, the more room for chaos."

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Heigl and husband Josh Kelley have been married for over five years and recently adopted their second child last April.

As for her specific advice for fellow celebrities who will soon be walking down the aisle, the 34-year-old former Grey's Anatomy actress said she recommends focusing on having fun rather than having a grandiose ceremony.

"I would say keep it intimate and small. I mean, you want to include all the people you love most, but ultimately it's really just kind of the best party ever and it should feel like that," she said. "It shouldn't feel like you have to stand in a receiving line for four hours thanking everyone for coming."

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Although weddings are joyous occasions for the bride and groom and their loved ones, marriage ceremonies are often portrayed as chaotic venues that serve as the convergence of various plotlines in the film world.

"That's what this movie does: It just brings together the chaos and the nightmare of planning a wedding and the stories of everybody's problems, but in the end, of course, it's very moving," said Diane Keaton, who highlighted that she has yet to be married.

Keaton, who play's Heigl's mother in the film, is joined by a slew of fellow veteran actors, including Robert De Niro, Susan Sarandon, and Robin Williams. Despite their long simultaneous tenures in Hollywood, Keaton divulged that she didn't know of any of them prior to the film.

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"...I knew none of the people my age," the 67-year-old actress said. "...It was really fabulous [to work with them]. Robin Williams came on the set and, of course, he's hilarious and to get to know Robert De Niro...was really a pleasure for me because he's so not what I thought he was."

Watch the full video to hear which actor Keaton would like to work with in the future. The Big Wedding is in theaters this Friday.