Jessica Simpson shows off super-skinny bod with sister Ashlee

Jessica and Ashlee Simpson could pass for twins! 

The sisters stepped out together at Macy's South Coast Plaza while supporting their joint venture, Jessica Simpson Girls collection, in Costa Mesa, Calif., on Saturday.

PHOTOS: Jessica Simpson's body evolution

Six months after welcoming daughter Maxwell with her fiancé, Eric Johnson, Jessica, 32, flaunted her slim figure in a blue blouse and black pants for photographers. Ashlee, 28, mother to son Bronx, almost 4, proudly posed next to her big sis and showed off their matching blond 'dos.

In late October, Jessica told Us Weekly she'd already lost 60 of the 70 pounds she gained during pregnancy with the help of Weight Watchers' PointsPlus program and four-times-a-week workout sessions with celebrity trailer Harley Pasternak.

PHOTOS: Her pregnancy with Maxwell

"I feel positive about how I've done so far and really good about the goals I have set," she told Us.

"Most people can tell a difference every time they see me," Jessica said, "which lets me know I'm making progress."

PHOTOS: Jessica's craziest Twitter pictures

Jessica and Ashlee's appearance Saturday was the first time the sisters have reunited in public since their parents decided to end their marriage. Joe and Tina Simpson confirmed to Us on Oct. 24 that they filed for divorce late September after 34 years of marriage.

"It is an amicable split and there is no third party involved. Any other related allegations are completely false," a family rep told Us. "The family appreciates your respect for their privacy at this time."

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