Ashlee Simpson took off from LAX yesterday with a friend, and some reading material. She set out for the trip hot on the heels of the news that she and her sister, Jessica, will be collaborating on a new Jessica Simpson Collection line for tweens. Jessica has already enjoyed huge success with her brand over the years, but says she can't wait to have Ashlee bring her rock-and-roll edge to this new endeavor. The Simpson siblings have been spotted out and about together frequently this Spring as they prep to launch the clothing and accessories range, but both ladies have also been focusing on the main men in their lives. Jessica has had her fiancé Eric Johnson by her side for most of her travels in 2011, and Ashlee has been clocking plenty of mommy-and-me dates with her toddler son, Bronx, since she filed for divorce from Pete Wentz in February.