Ashlee and Jessica Simpson posed together at Ashlee's engagement party to Evan Ross on March 26. Credit: courtesy of Jessica Simpson

Blonde beauties! Jessica and Ashlee Simpson looked bright and ethereal at the youngest Simpson's light-filled engagement party on Wednesday, March 26. The platinum blonde sisters posed together with Jessica, 33, in a form-fitted short white dress with silver embellishments and Ashlee, 29, in a bohemian, free-flowing tunic top and a giant feathered headdress. 

"Celebrating my best friend and sister @missbananahammock @ashleesimpsonofficial. I love her so much!" the mother of 22-month-old daughter Maxwell and 8-month-old son Ace captioned the photo

Ashlee couldn't have been more excited to celebrate her engagement to Catching Fire star Evan Ross. After attending their first event together in July 2013, Diana Ross' son, 25, popped the question in Hawaii on Jan. 13. 

"The love of my life said YES!!!!!!" he captioned a photo of Ashlee showing off her huge diamond ring at the time. This will be her second wedding after her previous marriage to Fall Out Boy's Pete Wentz, with whom she shares 5-year-old son, Bronx.

For the party, which appeared to take place in a picturesque back patio area with white lights and cozy couches, Ross sported an enormous grey fur coat while leaning in for a smooch with his fiancee. 

"What an amazing engagement party with all of our loved ones! We gettin' married :)" Ashlee captioned the romantic photo.