From PEOPLE Magazine Click to enlarge
Deafening piano notes, random guitar riffs and the plink of a xylophone-a kiddie jam session is in full swing at Martie Maguire's hillside Austin, Texas, home. Her three children-Harper, 1, and 6-year-old twins Kathleen and Eva-rock out on tunes they created with their cousins Gus, 7, and twins Julianna and Henry, 5 (Maguire's sister Emily Robison's kids). The audience of stuffed animals, dolls and Mommy seems rapt, listening to band favorites such as "Cow's Milk Is Good for You" and "Lollypop Tree." Says Mom with a laugh: "It's a fresh new sound."

After a four-year hiatus from the Dixie Chicks, Maguire, 40, and Robison, 37, were itching for some new tunes themselves. "The time off was torturous for me," says Emily, who was writing songs as a way to cope with her divorce from country singer Charlie Robison in 2008. ("I don't think I was the best person for him," she says of their amicable split.) So when frontwoman Natalie Maines Pasdar wasn't ready to hit the studio, the sisters recorded as the Court Yard Hounds (named for a fictional book in David Benioff's novel City of Thieves). "Emily wanted to pitch her songs to other artists at first, but they were so personal," says Maguire. (Sample lyrics: "We sat up all night while you apologized...But all I heard was the sound of the freedom bells ringing/ My heart breaking-it didn't make a sound.") "I told her she needed to sing them. I wanted to be a part of it."

Maguire had suffered her own heartache. With her 40th birthday not far off, she had a miscarriage while trying for a third child with her husband, Irish actor Gareth Maguire. "It was a big ordeal," she says. "I did another round of in vitro, and even though it was for our third baby, it was still all-consuming." And worth the struggle: Daughter Harper was born in 2008 and is already playing piano for the Ruffles.

It's all part of the Grammy winners' plans to fill their homes with music. "My kids go to appreciation classes where they get to try all kinds of instruments," says Robison, who shares custody with her ex. "They don't realize they're being taught, because it's so fun." The sisters have been duetting on multiple instruments, including guitar, banjo and violin, since their "orch dork" childhood in the Dallas suburb of Addison. By the time they were 12 and 10, the two had begun doing bluegrass shows together-but not without a push. "My parents had to bribe me with a water bed to get me to play my first gig," says Robison. Eight years later they formed the Dixie Chicks, and with Pasdar onboard since 1995, they've won 13 Grammys and sold more than 30 million albums.

And they're not done yet. "Bands take 10, 20 years off, so why are we dead?" asks Maguire, adding that the Chicks will kick off a tour with the Eagles June 8. Robison's love life is alive too: "I'm in a very happy relationship," she says, declining to name her new guy. Surely the Ruffles will be there to root the band on. Says Robison: "When the kids watch us, I see joy on their faces, because they know we love what we do."