Pregnant Nicky Hilton's Daughters Make Rare Appearance in Designer's Mother's Day Shoe Collection Campaign

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Nicky Hilton Rothschild is making this Mother's Day a memorable one with her girls.

The pregnant fashion designer, 38, was joined by daughters Lily-Grace Victoria, 5½, and Theodora "Teddy" Marilyn, 4, to announce her upcoming collaboration.

In PEOPLE's exclusive rare glimpse at Lily and Teddy, the girls wore matching outfits, coordinating with their mom in white and blue while having a tea party in their bedroom. Hilton is seen kneeling down with the two as they each sweetly kissed her on the cheek.

"My daughters definitely love fashion and dressing up. They usually gravitate towards Disney princess costumes and anything with unicorns or rainbows," Hilton tells PEOPLE. "I'm fully aware that I only have a few more years of dressing them in clothes that I pick, so I'm enjoying it while it lasts!"

Hilton shares her daughters with husband James Rothschild. The couple, who tied the knot in July 2015, is currently expecting their third child together, their rep confirmed exclusively to PEOPLE in January.

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For Mother's Day, Hilton is launching a shoe collection with longtime friend, alice + olivia CEO and founder, Stacy Bendet.

According to a press release, the fashion icons and mothers have designed ballet flats that feature prints that tie back to alice + olivia's spring collection. The floral flats, which are crafted in Spain by the Nicky Hilton x French Sole label, will release on April 28, just in time for Mother's Day.

"Stacey is not just one of my closest friends, but a fashion designer, philanthropist, and mother that I have long admired," Hilton tells PEOPLE exclusively. "Stacey has an incredible eye. We have been friends for over 20 years, and I have been wearing alice + olivia since I was a teenager. I was extremely excited to team up with her to create these limited-edition flats."

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"I love Nicky's style and design aesthetic," Bendet shares. "She's been my friend and muse for over 20 years and it is so fun to get to collaborate on shoes together! I love her emphasis on eco and sustainable materials, and I love how her flats pair back to all our spring dresses!"

The shoes will be available in Yellow and Green Drifting Floral and retail for $198 at NickyHilton.com, aliceandolivia.com and FrenchSoleShoes.com.