Psycho Sisters Susan Cowsill and Vicki Peterson release their duo debut

Crosby, Stills, Nash & Young, Cream, Blind Faith, the Traveling Wilburys, Velvet Revolver, Down, Temple of the Dog — all supergroups.

In harmony with supergroup criteria that requires members of the group to have experienced stardom with their previous bands, The Psycho Sisters qualify as a super duo.

The Psycho Sisters are New Orleans resident Susan Cowsill (the Cowsills, the Continental Drifters and a solo career) and former New Orleans resident Vicki Peterson (the Bangles, the Go-Go’s and the Continental Drifters).

Peterson is married to Cowsill’s older brother, John, who’s also a member of 1960s and beyond pop vocal group The Cowsills. This makes the Psycho Sisters real-life sisters-in-law.

Peterson and Cowsill first performed as a duo in 1991. These many years later they’ve released their album debut, “Up on the Chair, Beatrice.” Album release shows are set for Baton Rouge Thursday, Sept. 4, at the Red Dragon Listening Room, and New Orleans Friday, Sept. 12, at Chickie Wah Wah.

As The Psycho Sisters, Peterson and Cowsill’s voices blend naturally together in the 10 “Beatrice” songs, most of which are Peterson and Cowsill compositions. The duo also does a gorgeous remake of The Cowsills’ classic “Heather Says” and a charming take on the Harry Nilsson-penned Monkees song “Cuddly Toy.”

Busy through the years with the Bangles, Cowsills, Go-Go’s and Continental Drifters, Peterson and Cowsill nevertheless never forgot about The Psycho Sisters. Finally, in 2012, they recorded their first album at Dockside Studio near Lafayette.

“The Psycho Sisters existed in our hearts for all these years,” Peterson said from Los Angeles during a joint telephone interview with Cowsill in New Orleans. “We finally found that little window of time where we could physically get together and make the album happen.”

Reaction to “Up on the Chair, Beatrice,” a work distinguished by multi-layered vocals, skillful pop songcraft, bright, Byrds-esque guitars and some rootsy instrumentation has been overwhelmingly positive.

“I was going to send an email to our wonderful publicist,” Peterson said, “asking him, ‘Are you not sending us the bad reviews?’ ”

“Not everybody is going to be a fan, and that’s totally cool and OK, but I haven’t seen one negative thing either,” Cowsill said. “I think the spirit in which the album was made is being received in kind.”

Sixteen months apart in age, Peterson and Cowsill could, chronologically, easily be biological sisters. When they sing together, the two women hear a sibling blend. Cowsill noticed it from the day their voices first intertwined.

“It was clear that whatever that beautiful sibling, harmonious thing is, it was somehow coming out of two non-DNA-aligned bodies,” she said. “Susan kind of looked at me,” Peterson recalled. “She said, ‘You sound like my brother. This is weird.’ ”

“It is a gift, it’s magical,” Cowsill said. “What I hear right next to me when she’s singing, it’s like flying.”

Peterson’s biological sister and Bangles bandmate, Debbi, upon listening to The Psycho Sisters’ album, noted the special blend, too.

“Debbi said, ‘You guys have that sister thing,’ ” Peterson said. “And the genetic vocal blend in The Cowsills, The Andrews Sisters, in all of those family groups, has always been one of my favorite sounds on the planet.”

Cowsill, who performed with her mother and brothers in The Cowsills during her childhood in the 1960s and ’70s, inspired the then-aspiring Peterson to follow her musical dreams.

“My older sister said there was a girl in The Cowsills who was my age,” Peterson said. “I freaked out. ‘Wait a minute. What? She gets to play in a band.’ Because that’s all I wanted to do, already, and there was this little girl my age on ‘The Ed Sullivan Show.’ ”

Of course, Peterson grew up, became a member of the extremely successful Bangles, later joined the Continental Drifters, which featured the girl in The Cowsills, and latter still married that girl’s brother, John. And now Peterson sings in the duo called the Psycho Sisters with the girl she’d envied so much all those years ago.

“There is,” the still rather impish Cowsill noted, “something very much cosmic about this situation.”

The Psycho Sisters

WHEN: 8 p.m. Thursday, Sept. 4

WHERE: Red Dragon Listening Room, 2401 Florida Blvd., Baton Rouge

WHEN: 9 p.m. Friday, Sept. 12

WHERE: Chickie Wah Wah, 2828 Canal St., New Orleans