When Nile Rodgers' Chic released It's About Time, the disco-era outfit's first album in 26 years, the man known for producing platinum hits for David Bowie ("Let's Dance") and Madonna ("Like a Virgin") and for collaborating with Daft Punk ("Get Lucky") and Avicii ("Lay Me Down") added some Philly soul to his mix.

But that's nothing new. "Gamble and Huff were always an inspiration to Chic, and me, where orchestration, rhythm, and melody was concerned," Rodgers said.

Influence aside, Rodgers and his Chic partner, the late Bernard Edwards, wrote and produced Philadelphia's most famous expression of love and sorority, "We Are Family," with this town's heavenly harmonists, Sister Sledge. The 1979 We Are Family album — complete with the smashes "He's the Greatest Dancer," "Lost in Music," and "Thinking of You" — will be rereleased this month on the Rhino label's The Chic Organization 1977-1979.

It's a big deal to have one artist's boxed set — featuring Risqué (which yielded dance-floor classics such as "Good Times" and "My Forbidden Lover") — have another artist's work in it. But this 1979 Sister Sledge album is as much a part of Rodgers' artistry as it is the Philly sisters'.  Rodgers said, "This Sister Sledge album is just as much Chic as Chic, and the new heavy vinyl sounds just like we played it live in the first place. I was there. I should know, right?"

Rodgers and Chic's new It's About Time has two Philly through-lines. Rodgers credits Philadelphia-born jazz pianist McCoy Tyner with guiding his hand, literally. "My guitar style is based on McCoy; my right hand emulates his piano lines," said Rodgers.

The second Philly connection is when guest vocalist Elton John hits the microphone on "Queen," an It's About Time song that Rodgers wrote and arranged to emulate his love of orchestrator and songwriter Thom Bell, the third architect of the soulful Sound of Philadelphia. "That song is total Bell-level TSOP," said Rodgers. "I even used Bell's signature sitar sound."

As to why he chose Elton John for his R&B expression of womanly admiration and adoration, Rodgers recalled The Thom Bell Sessions, a Philly soul EP John recorded with Bell at 12th Street's Sigma Sound Studios in 1977 (home of Gamble, Huff, and Bell's best-known productions), that went unreleased until 1979. "That gritty soulful Elton — that's the voice I wanted for 'Queen,' " said Rodgers.

Kathy Sledge knows that Nile Rodgers knows a soulful voice when he hears it. "Nile's got the best ears," she said from her Los Angeles home (she still has a place outside Philly) before heading to a studio where she's writing music with Jimmy Jam of Jam & Lewis fame and bassist Stanley Clark. (She is also working on a theatrical musical about growing up with her sisters — her sister Kim is working on a film about the life of Sister Sledge. "There is madness in ours, as with any family, but we're still sisters," Sledge said. "When people nitpick, I just ask, 'Well, what's in your wallet?' "

" 'We Are Family,' as a song, is universal, and I'm asked to sing that and so many others around the world," said Sledge. "Life is a process, and I'm just processing it."

She's excited that "We Are Family" is getting new life with The Chic Organization box and remembers the story as though it happened yesterday. "Probably because I stay in touch with [former] Atlantic label president Jerry Greenberg, to the point of having lunch tomorrow," she said, laughing.

"Chic — Nile and Bernard — was hugely successful and were at a challenging part of their career. They didn't want to be seen as one-hit wonders and quickly offered hit songs to other artists on other labels. Atlantic, their home label, said, 'What about us?' and Chic wanted to see the roster. We were on that roster."

Sister Sledge had a few overseas hits for the label around 1977 and '78, but nothing yet in America, and they were ready for a great song, or eight. "I wasn't even 16 yet but wound up at the right place at the right time," said Sledge. "We had heard at that time Atlantic wanted Chic to produce the Rolling Stones but, instead, Nile wanted someone new, obscure, fresh. They wanted audiences to know that what they did was a hit because of them, not Mick Jagger's name. That was genius on Nile's part."

From there, Rodgers and Edwards began talking to the sisters about how "the birds of a feather flocked together," and Sister Sledge got themselves a custom-made hit based on their family life. And then they got seven more songs after "We Are Family."

Sledge mentions how Nile and Bernard were more spontaneous and free in the writing and production method than other producers Sister Sledge had worked with. "I was used to taking home material and working on it," she said. "Not with these guys. They believed in doing everything on the spot, and I never heard 'We Are Family' or any of the songs on that album until it was time to record it. I learned 'The Greatest Dancer,' as I was recording it. Sing a line. Cut. Sing a line. Cut. They were tough. But genius. That was the magic."

Rodgers and Sledge are still part of each other's lives — beyond the boxed set — with the nonprofit We Are Family Foundation  that seeks to empower youth. "Nile will always be in my life, just as my sisters will, as the ultimate family," she said. "And it all started in Philly."