"Evan and Ashlee have been friends for a really long time, probably ten years," a source told Us Weekly at the time. "They know each other from the club scene and have tons of mutual friends."
As if the event photos weren't enough proof, another source confirmed their relationship: "It helps that they were friends first. They have a long bond. They already know each other really well."
Ashlee wasn't only at the event for moral support. The 28-year-old singer and actress is the star of Jessica's fall line in a photo campaign shot by photographer Ellen von Unwerth (photos above).
Speaking to reporters at the event, Ashlee described her sister's style as a "bit more girlie."
"I kind of like to bring an edge to my looks. I do like to be in dresses, I just like to toughen it," she added.
"We were all having a good time, kicking dirt in pretty dresses. They did tell us to look for ticks! And I was like, 'OK, I'm just going to roll in the dirt,'" she said of the photo shoot, which you can see more of in the video below.