Question: When were the group, that provided vocals for 1974 hit TSOP, originally formed ?

Context articles: The Three Degrees
TSOP (The Sound of Philadelphia)
Real Ones
Music of Twin Peaks
Angela McCluskey
Rick Derringer
Paul Da Vinci
Masta Ace Incorporated
Jörgen Sandström
Star Baby

The Three Degrees are an American female vocal group, who were originally formed in 1963 in Philadelphia, Pennsylvania.
 Although a total of 15 women have been a member over the years, the group has always been a trio.
 The current line-up consists of Valerie Holiday, Helen Scott and Freddie Pool.
 Holiday has been a member since she first joined in 1967, while Scott has been a permanent member since 1976, having previously been in the group from 1963 to 1966.
 The group were particularly successful in the UK, achieving 13 Top 50 hit singles between 1974 and 1985.
"TSOP (The Sound of Philadelphia)" is a 1974 hit recording by MFSB (Mother, Father, Sister, Brother) featuring vocals by The Three Degrees.
 A classic example of the Philadelphia soul genre, it was written by Kenneth Gamble and Leon Huff as the theme for the American musical television program "Soul Train", which specialized in African American musical performers.
 The single was released on the Philadelphia International label.
 It was the first television theme song to reach number one on the "Billboard" Hot 100, and it is arguably the first disco song to reach that position.
Real Ones also known as Reelones, is a Folk/rock band from Bergen, Norway, which was formed in 1994 when the members were 14 and 15 years of age.
 Band members include Ivar Vogt (vocals, guitar, ukulele, saxophone), Jørgen Sandvik (vocals, guitar, banjo, sitar), Kåre Opheim (drums, backing vocals), Øystein Skjælaaen (bass, backing vocals), and David Vogt (vocals, violin, organ).
 1994-2009 Yrjan Tangenes provided vocals, percussion, and bodhrán, and Thomas Lønnheim played percussion in 1999-2000
The music of the American television series "Twin Peaks", its 1992 prequel film "", and its 2017 revival series was composed by Angelo Badalamenti.
 "Twin Peaks"' co-creator David Lynch wrote lyrics for five songs used throughout the series—including "Falling", "The Nightingale", "Into the Night", "Just You" and "Sycamore Trees"—and three songs featured in "Twin Peaks: Fire Walk with Me", including "A Real Indication", "Questions in a World of Blue" and "The Black Dog Runs at Night".
 Julee Cruise, who made cameo appearances in both the series and film, provided vocals for four of Lynch's and Badalamenti's collaborations, and jazz vocalist Jimmy Scott performed on "Sycamore Trees".
 Three of the series' actors—James Marshall, Lara Flynn Boyle, and Sheryl Lee—provided vocals for "Just You".
Angela McCluskey is a Scottish singer-songwriter based in California.
 She performs as a solo artist and as a member of the folk rock group Wild Colonials.
 McCluskey has also provided vocals for Curio and recorded the European dance hit and US Mitsubishi commercial hit "Breathe" among other songs with Télépopmusik (on albums "Genetic World" and "Angel Milk").
 Angela also sang "Beautiful Things" for American Express and more recently her voice can be heard on the Schick Quattro commercial singing "I’m Not the Girl".
 Her songs have appeared on the soundtracks for the films "Rachel Getting Married", "Sherrybaby", "The Beat That My Heart Skipped".
 Her music has also been featured in the TV series "Grey's Anatomy".
Rick Derringer (born Ricky Dean Zehringer; August 5, 1947) is an American guitarist, vocalist, Grammy Award-winning producer and entertainer.
 He came to prominence in the 1960s as a member of the McCoys, when he was brought in to record lead vocals for the number one hit single with "Hang on Sloopy".
 He then turned to blues rock, scoring a 1974 hit with "Rock and Roll, Hoochie Koo".
 He has worked extensively with brothers Edgar and Johnny Winter, and with the group Steely Dan.
 He also worked with "Weird Al" Yankovic, producing Yankovic's Grammy Award-winning songs "Eat It" and "Fat", and with the World Wrestling Federation, penning entrance songs for Hulk Hogan and Demolition.
Paul Da Vinci (born Paul Leonard Prewer, 1951) is a British singer and musician.
 He is best known as the lead singer on the 1974 hit recording by The Rubettes, "Sugar Baby Love", although he did not perform with the group at the time.
 He reportedly had a three-and-a-half octave vocal range, and worked as a demo and session singer before and after his own moderately successful solo career, which included the UK hit "Your Baby Ain't Your Baby Anymore", which peaked at number 20 in the UK Official Charts, week ending 17 August 1974
Masta Ace Incorporated was a Hip Hop crew formed by rapper Masta Ace.
 The group, also known as "The I.N.C.", included Eyceurokk (Eyce, Uneek and Rokkdiesel), Lord Digga, Paula Perry and R&B vocalist Leschea.
 Ace first gained notice in the rap world as a member of the legendary Juice Crew, and with the release of his acclaimed 1990 debut "Take a Look Around", which featured an appearance from Eyceurokk.
 In 1992, Ace formed the I.N.C. crew and recorded their first group album, "SlaughtaHouse", which was released in May 1993.
 Ace provided almost all of the rapping, with Lord Digga serving as the hype-man.
 Digga was also responsible for a bulk of the beats, producing five of the album's songs as part of the duo Bluez Brothers.
 Paula Perry was the main performer on the song ""Who U Jackin'?""
, Leschea provided vocals for ""Don't Fuck Around (Outro)"", and Eyceurokk appeared on the tracks '"Slaughtahouse"' (as MC Negro), ""Ain't U Da Masta"" and ""Saturday Nite Live"".
 The album was highly acclaimed, but sold only moderately well.
 Some versions of "SlaughtaHouse" included the hidden bonus track, ""Born to Roll"", which became a huge hit in 1994, breaking into the Top 25 on the "Billboard" Hot 100 singles chart.
 Eyceurokk split from the crew after "SlaughtaHouse", leaving the group to four members.
Jörgen Sandström of Stockholm, Sweden, provided vocals, bass and guitar for Grave on their first three albums and played with Entombed (Bass/Backing Vocals) 1995-2004.
 He is currently involved with bands such as Krux (Guitar), Vicious Art (Bass/Backing Vocals), The Project Hate MCMXCIX (Vocals) and Torture Division (Vocals/Bass).
 He also did guest vocals on Nasum's "Helvete" and on Death Breath's "Stinking up the Night".
"Star Baby" is a 1974 hit song by The Guess Who.
 It was written by Burton Cummings who also provided the lead vocals.
 It is classified in the genre of Power pop and was included on the group's LP entitled, "Road Food" as well as "The Guess Who – Greatest Hits" in 1999 and "The Guess Who - Anthology in 2003".
 The band performed the song on the "Midnight Special" television program on December 14, 1973.