Nicky Hilton Rothschild's daughters signed off on her latest fashion creations.

The 37-year-old designer launches her collaboration with childrenswear brand Dotty Dungarees on Saturday, featuring a collection of spring outfits for girls ages 6 months to 7 years old, and also available on Maisonette.

To pull off the adorable mother-daughter photoshoot that accompanies the launch, Hilton Rothschild tells PEOPLE she had to coax her girls — Theodora "Teddy" Marilyn, 3, and Lily-Grace Victoria, 4½ — with cupcakes to get their cooperation.

"Naturally, I had to bribe them with cupcakes, and it worked beautifully," says the mom of two. "Kids just do not like taking pictures. I remember growing up my parents trying to herd us all together for the Christmas card. It was the one day of the year we dreaded."

Hilton Rothschild says her daughters are "very girly girls" who gave their "stamp of approval" to Mom's new collection, especially the dresses. And the businesswoman has no plans to change up how she outfits her daughters for their everyday life.

"I love a pair of dungarees; it's such a classic staple. And I think today, a lot of parents are dressing their children in these hip, miniature adult outfits, which I'm not really a fan of," she says, adding, "I think children should dress like children."

What will Teddy and Lily-Grace not be wearing anytime soon? "Leather jackets and leather pants," she says. "They're just little kids! I don't know."

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Hilton Rothschild shares that her kids, whom she shares with husband James Rothschild, are beginning to develop their own senses of style, playing dress-up and creating imaginative ensembles.

"Both of my girls definitely love dressing up, and it started very young, at like 2 years old," she explains. "They love costumes and they love dressing up as princesses. ... Their bond is so sweet. A sisterhood bond is so special, and I love seeing that with my girls."

With Mother's Day approaching, Hilton Rothschild says she's looking forward to the special day — and what homemade gift Teddy and Lily-Grace have in store for her this year.

"Mother's Day at our house usually consist of lots of time in the kitchen and cooking a big breakfast. Then my girls love to bake, and they know I love to bake, so I'll make some cupcakes or brownies," she says. "Last year, they made me a big collage. They took all of my photos and cut them up and made this huge collage of my husband and I, our wedding pictures, our pets, everything."

Hilton Rothschild adds, "I do love Mother's Day. It's nice to have a special day dedicated to you."