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Grandaddy Garth has since issued a statement, asking the media for privacy as he celebrates the little one's arrival:
"Our family would first like to thank everyone for their warm wishes and sweet celebration of Baby K's arrival," he said. "Our children's lives have always been extremely private and they have been endlessly encouraged to be their own people. We have always wanted them to be individuals and NOT be known as 'someone's daughters.'"
He added: "I have been amazed and grateful how the press has always respected this. I now ask that respect to please continue as this young family begins the greatest days of their lives."
According to August's Facebook page, the new mom graduated from Owasso High School in 2012. She has been dating her daughter's father since 2011 and briefly attended college at the University of Oklahoma, but left after one year.
Brooks finalized his divorce from his first wife Sandy Mahl in 2001. The college sweethearts announced their separation in October 2000; they had three daughters together, Taylor, August and Allie, during their 14 years of marriage.
The best-selling solo artist, who has been in semi-retirement while he raises his three girls in Oklahoma, married longtime friend and collaborator Trisha Yearwood in December 2005.