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Joe Don Rooney ‘s little rascals officially outnumber him.

The Rascal Flatts guitarist and his wife, Tiffany Fallon , welcomed their third child — a girl! — on Monday, Sept. 29, in Nashville, his rep confirms to PEOPLE exclusively.

Born at 7:01 p.m. and weighing in at 6 lbs., 11 oz., daughter Devon Olivia joins siblings Raquel Blue , 4, and Jagger Donovan , 6.

“We are so thrilled to finally become a party of five,” the proud new parents tell PEOPLE. “Jagger and Raquel are so happy to be her big brother and big sister.”

With Rooney and the band busy out on the road, Devon’s big debut came just a little late.

“Our schedule is so crazy,” Rooney joked to Country Weekly in August. “I have literally a window of time from Sept. 22 through Sept. 26 off, so we’re hoping [her birth] falls in that window. No pressure, Tiff!”

As of August, the couple hadn’t decided on a name for their daughter just yet — possibly because the musician was busy counting down the days until her arrival.

“I’m just excited to have my wife back, bless her heart. She doesn’t do [pregnancy] very well,” he explained. “She’s been really sick with this one. She’s starting to feel a little better, she’s just in that uncomfortable stage now.”

In March, Rooney, 38, confirmed his family was “blessed” to be growing — and looking forward to having the new addition join in on the fun.

“Jagger and Rocky are very excited too. They’re going to make a great ‘big brother-big sister duo’ as the Rooney circus continues,” he joked.

— Anya Leon

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