Willie Nelson and his sister, Bobbie Nelson, are taking a trip down memory lane.

The country music–playing siblings are co-writing a memoir, Me and Sister Bobbie: True Tales of the Family Band, according to Rolling Stone. Bobbie Nelson, a pianist, has played with her younger brother’s band since 1973.

The book is being co-written by David Ritz, a prolific biographer who worked with Willie Nelson on his 2015 memoir, It’s a Long Story. He’s co-written memoirs with musicians Joe Perry, Paul Shaffer, and Buddy Guy.

Publisher Random House describes the book as “an inspiring, lyrical statement of how family always finds the way.

“In alternating chapters, this heartfelt dual memoir weaves together both their stories as they experienced them side by side and apart,” Random House says. “Willie and Bobbie have supported each other through unthinkable personal heartbreak, and they’ve always shared in each other’s victories. Through dizzying highs and traumatic lows, spanning almost nine decades of life, Willie and Bobbie have always had each other’s back.”The memoir is the first book by Bobbie Nelson. Her brother has written several books, including the novel A Tale Out of Luck and the memoir Roll Me Up and Smoke Me When I Die.

Me and Sister Bobbie is slated for publication on Sept. 15.

Michael Schaub is a Texas-based journalist and regular contributor to NPR.