On Thursday, Ashlee Simpson and her husband Evan Ross shared photos of their daughter Jagger and niece Maxwell — whom Ashlee's sister, Jessica Simpson, shares with husband Eric Johnson — twinning in matching flower girl dresses at a friend's recent wedding.
The boho maxi dresses, from girls & women's apparel brand Joyfolie, were in the color castor gray and featured a full tiered skirt with lace ruffles and a scalloped lace detail in the back.
Both cousins accessorized the looks with matching braid crown hairstyles for the day.
"Gorgeous Flower Girls," Ashlee, 37, captioned one snap of the two girls dancing outside the wedding venue.
In another photo, Maxwell wrapped her arms around Jagger's shoulders as the pair smiled at the camera. Ross also shared a sweet grayscale snap of the cousins hugging each other as they watched the bride and groom slow dance.
Maxwell, who celebrated her 9th birthday on May 1, is the oldest of three siblings. Jessica and Johnson also share son Ace Knute, 7, and daughter Birdie Mae, 2.
"I actually follow their lead in a lot of things," Jessica previously told Today's Hoda Kotb about her three children. "They have so much innocence. And they haven't had all the traumas and the dark stuff that we cling onto. And they're actually capable of making better decisions than we are."
Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human interest stories.
Speaking of her firstborn, Jessica raved, "My oldest, Maxwell, teaches me every day to surrender."
Jagger, who turned 6 years old in July, is also a big sister to baby brother Ziggy Blu, 9 months. She also has an older brother, Bronx Mowgli, 12, whom her mom Ashlee shares with ex-husband Pete Wentz.
RELATED VIDEO: Ashlee Simpson Shares First Photo of Children Bronx and Jagger with Their Newborn Sibling Ziggy
Last month, all of Jagger's siblings and cousins celebrated her 6th birthday. The American Girl doll–themed celebration saw Jagger and her friends enjoying treats around a colorful table where their favorite dolls also had seats next to them.
"Best girls party EVER. We love you @americangirlbrandofficial," Ashlee wrote on one slide of her Instagram Story.
In another post, the proud mom paid tribute to her only daughter, who wore a crown that read "Happy Birthday" for the occasion. "HAPPY BIRTHDAY to my little princess 🦄 You are the brightest light. We love you 🥳💚," wrote Ashlee.