"Ireland has yet to meet Carmen, but we're excited for her to find the time to come over here and meet this little one," Hilaria tells VanityFair.com.
Shortly after the birth was announced on Aug. 23, the 17-year-old model posted a letter to Carmen and welcomed her into the world.
"You have been born into one crazy family," the daughter of Alec and Kim Basinger writes in the 1800 word note. "You are both lucky and cursed at the same time. We are going to have so much fun together."
While Alec, 55, and the yoga instructor are based in NYC, Ireland lives and works in LA, which would explain why it's been hard for her to fly cross-country.
But Hilaria tells VF that Carmen is "very lucky" to have the teen as a big sister. She even joked that they'll one day be chatting in cafe, reminiscing — as the reporter points out — on "how Channing Tatum used to be hot."
"They'll be doing that, and Carmen will be like, Who is Channing Tatum?" the 29-year-old says.
In the story, which promotes her new Fit Mommy-to-Be Prenatal Yoga DVD, Hilaria also talks about how helpful Alec was during her pregnancy.
"I did most of my yoga on my own, but he definitely helped me out. And part of the DVD is partner stretches," she shares. "He would do the three that we have on [the video below]. Arches and pains are a normal part of pregnancy, and he was really great at helping me alleviate them through yoga stretches."