The mother of three shared a late summer photo of her girls wearing cute Hawaiian-print outfits

Jessica Simpson‘s daughters have one thing to say: Aloha!

The singer, 39, shared an adorable photo of Maxwell “Maxi” Drew, 7, and Birdie Mae, whom she and husband Eric Johnson welcomed in March of this year, on Wednesday. The couple also share son Ace Knute, 6.

In the snap, Maxi holds her little sister up for the camera, and both sport Hawaiian-print outfits. Little Birdie also wears an adorable straw hat, while Maxi’s long blonde hair is done in a side braid (it looks like the pink she added to her ends earlier this month may have washed out).

“Aloha from my girls 🌺 #MAXIDREW #BIRDIEMAE” Simpson wrote in the caption for the snap.

Simpson (who celebrated her birthday with a glamorous poolside party just last month) told PEOPLE in July that their house has gotten a lot busier with the addition of Birdie.

“Three kids is no joke. It is definitely constant, and the biggest challenge for me is trying to be present when I am pulled in so many directions,” she said. “They are all in such different phases now.”

Of parenting with her former NFL player husband, Simpson added that “there is a lot of dividing and conquering going on right now at our house.”

To make things even busier for the star, she recently announced that she is writing a memoir, which is expected to drop in February 2020.

Jessica Simpson
Jessica Simpson’s daughters
| Credit: Jessica Simpson/Instagram

“I have been approached many times over the years about writing a book. It never felt right to me until this very moment,” she told PEOPLE exclusively in July. “I have always felt that one of my God-given purposes in this life is to inspire people.”

“I hope that by telling my whole story and not holding back I can help move people to walk through their fears and defeat their challenges, as I am working hard to do every day with mine. I hope readers will feel the love, laughter, tears and truth contained in every page,” she added.

But despite a busy schedule, it’s clear Simpson loves being a mother of three — and celebrating the special bond her children share. The star certainly hasn’t shied away from sharing photos of their sweet sibling relationship.

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Jessica Simpson
Jessica Simpson, Eric Johnson and kids
| Credit: Jessica Simpson/Instagram

“I love the way he loves her 💕 #ACEKNUTE #BIRDIEMAE” she said in the caption of a photo of Ace with Birdie just 11 weeks after her youngest child was born.

She also shared a photo of Maxi reading to her baby sister, saying in the caption, “I love the way she loves her 💕 #MAXIDREW #BIRDIEMAE”

In May, Simpson shared another shot of the sisters, saying in the caption that “These ladies make my heart burst with love sprinkles.”