Ashlee Simpson hit ex-boyfriend Ryan Cabrera's birthday party with her new fiancé Evan Ross. Jessica Simpson's sister, who got busted on SNL for lip-syncing, was locking those lips at the bash.

The 29-year-old pop star and actress got engaged to actor Evan Ross earlier this year. The pair were there to help Ryan Cabrera ring in his 32nd birthday at the Kia Motors Malibu Estate in California on Sunday.

According to sources, Ashlee and Evan Ross spent the night in heavy PDA mode. That is when Ashlee wasn't trying to get Evan to listen to some of Cabrera's new songs.

An eyewitness told Us weekly "They were both super cute with one another, very affectionate and very touchy feely. At one point Ashlee even had Evan sitting on her lap as they conversed with their friends. ... ''At one point Ashlee even had Evan sitting on her lap as they conversed with their friends.''

Ashlee and Ryan are still close friends, but since they broke up, Ryan dropped Ashlee's father, Joe Simpson, as his manager. Ryan is currently working on on a new album.

A surce told Us Weekly that Ashley spent the night "urging Ryan to play his new record for Evan so he could listen to it and maybe give him some insight on some lyrics that Ryan was struggling with. Evan and Ryan talked about collaborating and getting in the studio together. Both of them sounded super stoked on the idea and will be making it happen sooner than later."

Ashlee Simpson will be marrying Evan Ross later this summer. This will be Ashlee's second marriage. Her sister Jessica married former NFL star Eric Johnson earlier this month

Ashlee  has a five-year-old son Bronx with her ex-husband Pete Wentz.