Joni Sledge, who has died aged 60, sang with her siblings in Sister Sledge, the US group whose disco-era smash We Are Family transcended its origins to become an anthem for female empowerment.
By the late 1970s, the four sisters in the band - Debbie, Joni, Kim and Kathy - were becoming frustrated at gaining only minor success. Kim had started law school.
Their record label, Atlantic, then teamed them with the producers and songwriters Nile Rodgers and Bernard Edwards, who as the band Chic embodied the hypnotic rhythms of disco. The sessions would yield four huge hits that in 1979 brought the group international recognition: He's the Greatest Dancer; Lost in Music; Thinking of You (which charted in 1984); and the title track of their platinum-selling LP, We Are Family.
The extrovert Joni Sledge later recalled its recording as a "one-take party". The band's tight choreography, bright costumes and euphoric style propelled the single to No 2 in the US chart (No 5 in the UK) as it sold more than one million copies. Its chorus -"We are family, I got all my sisters with me" - might have been merely the literal truth, but it came to be adopted by women as a celebration of their strength and unity.
Joni Sledge was born in Philadelphia on September 13 1956. She was the third of five girls, of whom the eldest Carol became a teacher. Their parents were Edwin, a tap dancer who appeared in the original Broadway production of Kiss Me Kate, and Florez, an actress.
The pair were divorced when the children were young, and it was their mother's example that inspired the girls. Florez held down several waitressing jobs at once and joked later that her daughters learnt to sing because they were locked in the house for much of the day to stop them wandering the streets.
They acquired the name Sister Sledge when announced on stage by an MC unsure what they were called.
Joni excelled at school and later studied for a degree in Communications at Philadelphia's Temple University. None the less, by the time Joni was in her mid-teens, Florez had taken the group on the road.
In 1974 they performed at the concert before the "Rumble in the Jungle" fight in Zaire between Muhammad Ali and George Foreman. Gwen Guthrie began to write songs for them and the next year they had their first hit, Mama Never Told Me, which reached the Top 20 in Britain.
After their major successes, they continued to release albums, and in 1985 had their only UK No 1, with Frankie. Kathy left the group four years later and Joni took on more responsibility. She produced their LP African Eyes (1997), being nominated for a Grammy, and wrote the protest song Brother, Brother Stop after witnessing a shooting.
In 2000, Sister Sledge played at President Clinton's last Christmas party at the White House. Five years later they performed at Glastonbury, and in 2015 footage of them singing We Are Family for Pope Francis went viral when nuns in the audience danced along.
Joni is survived by a son.