The shape of A.J. McLean‘s heart? Full.
Now almost 3 weeks old, little Lyric — who joins 4-year-old Ava Jaymes — has already captured the hearts of her parents and her big sister, who has been preparing for her role for a while.
“Seeing the excitement and anticipation that Ava has about being a big sister is truly amazing, and the best feeling in the world,” McLean, 39, tells PEOPLE. “She’s been practicing for months with her dolls, and with some of my wife’s friends’ babies.”
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McLean admits that the possibility of adding to their family was something that became gradually more appealing, due in large part to his older daughter.
“I was told by someone very dear to me that having a child will change you forever, and that was beyond true with Ava,” he says. “We decided to try one more time because even though Ava is so independent, the idea of having a sister or brother for her became more and more important to us.”
Adds the singer, “Having two baby girls is a dream come true and we couldn’t be any more proud or excited to welcome Lyric Dean McLean into the world and into our family.”
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It sounds like two might be the magic number for the couple, who come from very different sets of siblings (or, in McLean’s case, a lack thereof).
“Despite the fact that I’m an only child and (all jokes aside) turned out okay, my wife is one of four and that showed me there’s something beyond special about having siblings,” he explains.
McLean announced on social media in September that his family would be growing, revealing the baby’s sex in October. Speaking to Entertainment Tonight, he quipped, “A lot of girls in the house! Girl power all the way! All my boys have boys, so it’s nice to have girls.”
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The singer is currently coming off of the premiere of his “Backstreet Boys: Larger Than Life” Las Vegas residency at Planet Hollywood Resort & Casino, which kicked off March 1 and will return April 12 after a month-long hiatus.
Of his wife of five years, McLean added to ET that she was due “literally just shy of a week after,” the show’s hiatus, joking, “Hopefully I’m not in the middle of the show and all like, ‘I have to go!’ ”
“Backstreet Boys: Larger Than Life” at Planet Hollywood’s Axis in Las Vegas returns for select dates between April 12 and 28, then again between June 15 and July 1. You can buy tickets here or here, and book a stay here.
For more from A.J. McLean, pick up the latest issue of PEOPLE, on newsstands now.