"When they put Dakota in our arms, he has the most beautiful smile, and the moment Kenny started talking to him, Dakota lunged toward him," Christiev tells PEOPLE of their baby boy, now 9-months-old. "We both looked at each other and it was like, 'Of course he is our son.' "
Big Kenny (whose full name is Kenny Alphin), 46, and his wife already have a 4½-year-old son, Lincoln William, together and they decided to adopt domestically after unsuccessfully trying for a second child.
"Having Lincoln as an only child was wonderful but I come from a large family and I didn't want him alone," says Christiev, 47. "Even when Kenny and I were dating I asked him about adoption and he said absolutely, so our hearts and minds were open."
Lincoln "has had to learn how to be a sibling," but he's a quick study. "Lincoln is in love with him – he says Dakota is going to play keyboards in his band," she says. "He's aware of a beautiful responsibility."
And though Dakota's a newcomer, he's already a perfect fit. "This child is so happy and so boisterous," she says. "He lunges to kiss and hug and he sings all the time!"