The sisters stepped out with husbands Evan Ross and Eric Johnson at a party celebrating Linda Perry
Credit: Frazer Harrison/Getty

These sisters know how to rock.

On Tuesday, Jessica Simpson and her sister Ashlee Simpson had a moms’ night out with their husbands Eric Johnson and Evan Ross at a private party in West Hollywood, California, celebrating hitmaker Linda Perry and the song “Hands of God” from the film Freeheld.

Sipping on wine and cocktails throughout the night, the sisters – both decked out in black – danced and sang along as Perry, Juliette Lewis, Courtney Love and Christina Aguilera performed in front of the intimate crowd. Perry’s wife Sara Gilbert and her The Talk co-hosts Julie Chen, Aisha Tyler and Sharon Osbourne also came out to support.

“Ashlee and Evan acted like newlyweds,” says an onlooker. “They were cuddled up together in a booth, laughing and showing off cute PDA. Jessica looked really happy to be hanging out with them and seemed to get along great with Evan.”

Also at their table were longtime Simpson pals CaCee Cobb and Donald Faison, who chatted with Johnson while Jessica talked with her friends.

“Eric and Jessica did their own thing at the party and would check in on each other every now and then,” says the source. “He came over to introduce himself to her friends a few times and would run close to the stage to take photos of the performances.”

Around 9 p.m., Aguilera made her way to the stage to sing “Mother” by John Lennon.

“Her fiancé [Matt Rutler] held her hand on the way up,” says the source. “She said she was getting over the flu but wanted to come and support Linda.”