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(Yahoo!) - Ashlee Simpson is going to the chapel — but first there's the matter of her engagement party.

The 29-year-old celebrated her impending nuptials to Evan Ross over the weekend with a lavish celebration attended by family — like her big sister, Jessica — and friends. And on Wednesday night, she took to Twitter to gush about the bash.

The pair, who announced their engagement in January, were dressed to the nines for their party. In the photo, the blonde had on headband with large white feathers and a drapey dress with big sleeves as she smooched her future groom, who was wearing a short-sleeve furry coat with a long-sleeve white shirt under it.

Jessica — looking amazing in a white and silver mini-dress, thanks to Weight Watchers — also posted a photo in which she's posing with her sis, who has a 5-year-old son with ex-husband Pete Wentz.

"Celebrating my best friend and sister @missbananahammock @ashleesimpsonofficial," the mom of two, who is also planning a wedding, wrote on Instagram. "I love her so much!"

Evan, who is the son of the legendary Diana Ross (who turned 70 on Wednesday), also shared a couple family snapshots. In addition to a sweet one of him and his mom, the Hunger Games: Mockingjay – Part 1 actor posted a second one in which he's planting a kiss on his "Bat for a Heart" singer love while two of his sisters — Chudney Ross and Tracee Ellis Ross, in her lip dress — look on.

The outdoor party space was decorated with shimmering white lights, setting the perfect mood for the fete. And Ash wasn't alone in sporting feathers. The couple's cake had white and tan ones at its base with their initials, A and E, on top, as you can see in this Instagram pic posted by actor and party guest Daniel Booko.

With an engagement party so beautiful, we have great expectations for their wedding day.