buddy system; Great mix-and-match looks are guaranteed when interior designers Kelly Behun and Natasha Ziff wear Derek Lam and Zac Posen.

Byline: Lynn Yaeger

We're going for a chic-mom look. No matter how sleep-deprived and harried we are, we want to look pulled together,'' says Kelly Behun, one half, with Natasha Ziff, of Behun Ziff Designs, an interior-design business they started three years ago. Behun and Ziff each have two preschool-age children, but that doesn't mean they've abandoned those hallmarks of the stylish woman: a beaded Jamin Puech handbag, say, on Ziff's elbow; or a shrunken Chanel jacket jauntily draped over Behun's shoulders.

And sometimes it's the same hallmark. Laughing and interrupting each other, the women tell a story of how they played hooky one afternoon and dashed off to H&M. Just as they occasionally add a splash of IKEA to an elegant home they're working on-"our approach is to mix periods, styles, and price points," says Behun-they thought perhaps they'd find a little something at the bargain clothing chain.

It was not to be. "We looked at each other and said, 'We're too old for this place,' " Behun recalls; they turned and crossed Fifth Avenue to Gucci, where they proceeded to fall desperately in love with the same jacket. "It's a mushroom color with these epaulet things on the shoulder," Ziff says of their simultaneous ...