Question: Were the songwriters Bruce Guthro and Ronald Isley both members of the music group the Isley Brothers?

Context articles: Brother, Brother, Brother
It's a Disco Night (Rock Don't Stop)
Ronald Isley
Masterpiece (The Isley Brothers album)
Mission to Please
Choosey Lover
Baby Makin' Music
That Lady (song)
Bruce Guthro
Eternal (The Isley Brothers album)

Brother, Brother, Brother is the tenth album released by The Isley Brothers on their T-Neck imprint on May 2, 1972.
 It was to be the Isleys' last studio record with Buddah Records moving on to Epic in the middle of 1973.
 This album also was the first to bring the younger half of the Isleys: guitarist Ernie Isley, bassist Marvin Isley and keyboardist Chris Jasper into the fold alongside their older brethren: lead singer Ronald Isley and background singing elder brothers O'Kelly Isley, Jr. and Rudolph Isley.
 Their second venture into rock music, they didn't betray their soul and funk roots.
 The album featured the top 40 hit, "Pop That Thang", and subsequent hits "Work to Do", "Lay-Away" and their cover of Carole King's "It's Too Late".
 The brothers also covered two more King songs including the title track and "Sweet Seasons".
"It's a Disco Night (Rock Don't Stop)" is a 1979 club hit for The Isley Brothers, released on their T-Neck label as the second single from their gold-certified album, "Winner Takes All".
 The song is notable for being one of the few disco-based songs the Isley Brothers released.
 Beforehand, the group were known for their mixture of funk, rhythm and blues and rock.
 The song was led by brother Rudolph Isley while his brothers Kelly and Ronald Isley chanted "rock don't stop" in the background.The song briefly charted on the "Billboard" Hot 100 peaking at number 90, hitting number 27 on the R&B chart.
 Outside the US, "It's a Disco Night" reached number 14 on the UK Singles chart.
Ronald Isley ( ; born May 21, 1941) also known as Ron Isley and Mr. Biggs, is an American recording artist, songwriter, record producer, and occasional actor.
 Isley is best known as the lead singer and founding member of the family music group the Isley Brothers.
Masterpiece is the 23rd album released by The Isley Brothers on Warner Bros.
 Records on April 29, 1985.
 For the first time since 1973, the Isley Brothers were a trio composed of the original members O'Kelly, Rudolph and Ronald Isley.
 It was the last album with O'Kelly Isley; he died a year after the album's release from a heart attack.
 The album is dedicated to their late brother Vernon Isley and their parents Sally & O'Kelly Isley Sr.
 The album liner notes were written by Elaine Isley.
Mission to Please is the 27th album by The Isley Brothers, released on May 14, 1996, on Island Records.
 It was a return to commercial glory for the group in the years following their platinum-certified album "Between the Sheets" (1983).
 Mission to Please also went platinum based on the strength of the charted singles "Let's Lay Together," a new duet with R. Kelly after the success of "Down Low (Nobody Has to Know)" (1995); the Babyface-composed ballad "Tears"; "Floatin' on Your Love," featuring Angela Winbush (Ronald Isley and she were married from 1993 to 2002); and the mid-'90s quiet-storm radio staple "Mission to Please You."
 Some of the album's success was due to Ronald Isley cultivating a new image as the character of "Mr. Biggs" in a series of R. Kelly videos, starting with "Down Low," helping to introduce the music of the Isley Brothers to a new generation of R&B fans.
 "Mission to Please" is the last Isley Brothers album to feature youngest brother Marvin Isley, who left the group in 1997 because of complications from diabetes; he died on June 6, 2010.
 "Mission to Please" also helped relaunch the Isley Brothers' label, T-Neck Records.
"Choosey Lover" is a 1983 quiet storm soul song by The Isley Brothers (Originally titled "Juicy Lover").
 Released on their T-Neck imprint, the song was their second consecutive top ten R&B hit after their seminal "Between the Sheets" hit No. 3 on that chart.
 It was the second of two chart-topping singles the Isleys released off their aptly titled "Between the Sheets" album.
 "Choosey Lover" was also the last charting single to feature the "3 + 3" lineup of the band.
 A year later, younger brothers Ernie Isley (who played the memorable guitar solos on the song and co-wrote the lyrics), Marvin Isley and their brother-in-law Chris Jasper left to form Isley-Jasper-Isley while older brothers Ronald Isley, Rudolph Isley and O'Kelly Isley continued on under the "Isley Brothers" name.
Baby Makin' Music is the 30th studio album released by The Isley Brothers on the Def Soul Classics imprint on May 9, 2006.
 Their first for the Def Jam-affiliated label, the album peaked at No. 5 on the album charts based on the R&B chart success of the first single, "Just Came Here to Chill", and the R. Kelly duet, "Blast Off", which is the only collaboration with Kelly on the album, after single-handedly producing their last album, "Body Kiss".
 Other producers included Gordon Chambers, Jermaine Dupri, Tim & Bob and Manuel Seal.
 Except for two songs ("Forever Mackin'" and the suggestive "Give It to You"), much of this album is dedicated in love to Ronald Isley's new wife, Kandy Johnson, of his background singing group, JS (Johnson Sisters).
 He even steadfastly claims in "Just Came Here to Chill" that he's not into playing the Mr. Biggs part and he's "just Ronald Isley" while the couple decided to spend time together at home.
 The album closer, "You Help Me Write This Song", which was co-written by Isley, was played at his and Johnson's September 2005 wedding.
"That Lady" is a 1973 R&B and soul song by The Isley Brothers, released on their T-Neck imprint.
 The song was originally performed by the group nearly a decade before in 1964 (released as "Who's That Lady?")
 inspired by The Impressions.
 After signing with Epic Records in 1973, the eldest members of the group (O'Kelly Isley, Jr., Rudolph Isley and Ronald Isley) had included younger members, guitarist Ernie Isley, bassist Marvin Isley and keyboardist/pianist Chris Jasper, as official members.
 In a response to this transformation, the group gave themselves the moniker of "3 + 3", describing the three original vocalists in the group and three recruited instrumentalists, inspiring the album title that came out that year.
 They performed the song on "Soul Train" on December 14, 1974.
Bruce Guthro (born Bruce Guthrie on August 31, 1961) is a Canadian singer / songwriter, from Cape Breton Island, Nova Scotia.
 Guthro has recorded as a solo artist, and in 1998 joined the Scottish folk rock band Runrig, whilst still pursuing his solo career.
 Guthro has received several ECMA's (East Coast Music Awards), and has hosted the Canadian TV show "Songwriters Circle", on which guests included Alan Doyle, from the Canadian Band Great Big Sea.
 Guthro also appeared at the Tønder 2007 Festival.
Eternal is the 28th album released by The Isley Brothers on DreamWorks Records on August 7, 2001.
 Now popular again with audiences, almost single-handledly for Ronald Isley's "Mr. Biggs" persona, "Eternal" included production from not only R. Kelly who gave the Isleys their biggest hit as leading artists in over two decades with "Contagious" but also from Jimmy Jam & Terry Lewis, Raphael Saadiq and Ronald's wife at the time, Angela Winbush.
 Based on the mega-success of "Contagious", "Eternal" peaked at #3 on the "Billboard" Billboard Top 200 album charts and #1 on the R&B album chart selling over two million copies having it certified double-platinum.
 The first album the Isleys released as a duo in over a decade (Marvin Isley left the group after suffering a bout with diabetes, which later caused both of his legs to be amputated), Ernie Isley also showcase his talents as a guitarist in songs like "Move Your Body" and the aptly titled "Ernie's Jam" while Ronald was still as vocally strong on this album as he had been throughout the Isley Brothers' legendary catalogue.