Jessica & Ashlee Simpson bring sister act to fashion

(CBS) Ashlee Simpson is following big sister Jessica into fashion in much the same way she followed her into music.

The two sisters are teaming up to create a new 'tween clothing line, making fashion, as well as singing, a family affair.

Pictures: Famous sisters
Pictures: Jessica Simpson
Pictures: Ashlee Simpson

Jessica Simpson has been making a lot of money - Women's Wear Daily predicts she will reach $1 billion in sales this year - with her Jessica Simpson Collection of clothing, shoes, handbags and accessories.

Now she and Ashlee, who sports a decidedly rocker style, are taking aim at the same market Madonna and daughter Lourdes have been courting with their Material Girl line.

"Creating a tween apparel collection was a natural extension for the brand," the soon-to-be married Jessica tells Women's Wear Daily. "I'm excited to bring my sister, Ashlee, along as co-creative director of this division, because she brings a savvy rocker edge that defines today's 'tweens."

The soon-to-be divorced Ashlee said, "My goal as co-creative director will be to design clothes that will help inspire young girls to express their personalities and creativity through fashion."

The first designs are expected to hit store shelves for back-to-school shopping and will be available at Macy's, where Jessica Simpson is already promoted in store commercials, and Lord & Taylor.