Sylvester Stallone's daughters are definitely ready for their own time in the spotlight.

Case in point? Sophia, 20, Sistine, 18, and Scarlet, 14, stun on the cover of Harper's by Harper's Bazaar's May issue.

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ET's Carly Steel caught up with the sisters at the magazine's cover party in Los Angeles on Thursday, where they opened up about their latest gig, and the one thing they never fight over.

"I'm still in shock," Sistine revealed of the sisters' beautiful cover. "I think we're all still really in shock from this moment because when we actually found out that we got the Harper's Bazaar cover, it was the three of us."

"We thought it would stop at the Hollywood Reporter," Sophia explained. "And then all of a sudden they were like, 'Oh, Harper's Bazaar is here.'"

The girls have looked perfectly coordinated in every appearance since their 2017 Golden Globes debut in January -- though they admit working together is harder than it looks.

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"I mean, we're sisters, we fight about everything" Sistine confessed. "That's why it's really good, and especially for my mom, when we all get the same job. She's like, 'I can sit back and relax.'"

"But I think jobs aren't something we compete over. We're really supportive when one of us gets a job," Sophia added. "But I think, yeah, we're like [competitive] clothing-wise. That's competitive."

It's a good thing the sisters are supportive of each other's careers, as they've got quite a few gigs in the pipeline.

"I think ever since the Golden Globes, we've really been taking off more. I feel like we've been getting a lot more jobs," Scarlet said.

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"Totally. We've had so many opportunities and we're so lucky. We never in a million years thought that this would all be coming out of the Golden Globes," Sistine shared. "Of course, it was a huge deal, but we kinda thought it would end there. So the fact that this is kind of a snowball effect and we keep getting jobs and covers [is amazing]."

"Actually, recently we just got our first Australian campaign together," Sophia added. "[And we've done] photo shoots for Dolce & Gabbana recently. They're still coming out."

"It doesn't get [any] better," Sistine said.

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