Question: Graham Bonnet and John Corabi, have which mutual occupation?

full_context: Document 1: John Corabi: John Corabi (born April 26, 1959) is a hard rock singer and guitarist who has worked with such bands as Angora, The Scream, Mötley Crüe, Union and ESP (both with former Kiss lead guitarist Bruce Kulick), Ratt (as a guitarist), Twenty 4 Seven (with his then Ratt bandmate Bobby Blotzer), Zen Lunatic, Brides of Destruction, and Angel City Outlaws (with his then Ratt bandmates Robbie Crane and Bobby Blotzer, and former Ratt guitarist Keri Kelli, who he replaced in Ratt). He is the current lead singer for The Dead Daisies.
Document 2: Jimmy Crespo: James Crespo, Jr. (born July 5, 1954 in Brooklyn, New York) is an American guitarist. He was the lead guitarist for Aerosmith from 1979 until 1984. He co-wrote "Rock in a Hard Place" with Steven Tyler, and has performed or recorded with Rod Stewart, Billy Squier, Meat Loaf, Stevie Nicks, Robert Fleischman, Rough Cutt, Renegade, Flame and others.
Document 3: Robbie Crane: Robert Crane (born January 5, 1969 in Orange County, California) is the current bass guitarist with hard rock band Black Star Riders. He is also a member of Ricky Warwick's band The Fighting Hearts. He was previously the bassist with the band Ratt.
Document 4: Lou Gramm: Lou Gramm (born Louis Andrew Grammatico; May 2, 1950) is an American rock singer, and songwriter, best known for being the original lead singer of the British-American rock band Foreigner.
Document 5: Mötley Crüe (album): Mötley Crüe is the eponymous sixth studio album by American heavy metal band Mötley Crüe. It was released on March 15, 1994, and is the only album that does not feature lead singer Vince Neil, who had departed from the band in 1992. Neil was replaced by former The Scream vocalist John Corabi on the album.
Document 6: Jim &quot;Dandy&quot; Mangrum: James Mangrum (born March 30, 1948), better known as Jim "Dandy" Mangrum, is the lead singer and frontman for the American Southern rock band Black Oak Arkansas. He is noted for his raspy voice, long hair, and wild, sexually-explicit stage antics which sometimes included miming sex with a washboard which he often uses to accompany his singing. His stage persona is credited as having been a major influence on Van Halen vocalist David Lee Roth.
Document 7: Doug Aldrich: Doug Aldrich (born February 19, 1964) is a Los Angeles-based hard rock guitarist. He founded the band Burning Rain with Keith St. John in 1998 and has played previously with the bands Whitesnake, Dio, Lion, Hurricane, House of Lords, Bad Moon Rising and Revolution Saints. He is currently in the band The Dead Daisies. He has also released several solo albums. In 2015, Doug was touring as guitar player of former Deep Purple bassist and vocalist Glenn Hughes band. In early 2016 it was announced that he would be replacing Richard Fortus as guitarist of The Dead Daisies, as Fortus is leaving that band to perform with the Guns N' Roses reunion.
Document 8: Graham Bonnet: Graham Bonnet (born 23 December 1947) is an English rock singer and songwriter. He has recorded and performed as a solo artist and as a member of several hard rock and heavy metal bands including Rainbow, the Michael Schenker Group, Alcatrazz, and Impellitteri. Bonnet is known for his James Dean-inspired style and extremely powerful singing voice and wide vocal range. His singing has been noted as 'very loud' by both his contemporaries and himself, and he claims to be a self-taught singer with 'no discipline for lessons'.
Document 9: Rob Halford: Robert John Arthur Halford (born 25 August 1951) is an English singer and songwriter, who is best known as the lead vocalist for the Grammy Award-winning heavy metal band Judas Priest and famed for his powerful wide-ranging voice. AllMusic says of Halford: "There have been few vocalists in the history of heavy metal whose singing style has been as influential and instantly recognizable", possessing a voice which is "able to effortlessly alternate between a throaty growl and an ear-splitting falsetto". Halford was voted number 33 in the greatest voices in rock by Planet Rock listeners in 2009. In addition to his work with Judas Priest, he has been involved with several side projects, including Fight, 2wo and Halford. In 1998, he came out as gay in an interview with MTV News.
Document 10: Union (band): Union is an American rock group formed in 1997 featuring lead vocalist and guitarist John Corabi (ex-The Scream and Mötley Crüe), guitarist Bruce Kulick (ex-Kiss), bassist James Hunting (David Lee Roth and Eddie Money), and drummer Brent Fitz (Slash).
Document 11: Suggs (singer): Graham McPherson (born 13 January 1961), known by the stage name Suggs, is an English singer-songwriter, musician, radio personality and actor.
Document 12: Eric Singer Project: Eric Singer Project is an American rock band. ESP was founded in the 1990s by Eric Singer, drummer for such acts as Lita Ford, Black Sabbath, Badlands, Alice Cooper, and Kiss, along with Bruce Kulick (Kiss, Grand Funk Railroad) on guitar, John Corabi (The Scream, Mötley Crüe, Ratt) on guitar and bass, and Karl Cochran on guitar and bass. Vocals duties were shared by Eric, John, and Karl.
Document 13: Ian Gillan: Ian Gillan (born 19 August 1945) is an English singer and songwriter. He originally found commercial success as the lead singer and lyricist for Deep Purple.
Document 14: Underground (Graham Bonnet album): Underground is the fifth solo album by English rock singer Graham Bonnet, originally released in 1997. "Underground" reunites Bonnet with guitarist Danny Johnson, who previously performed with Bonnet in Alcatrazz. "Lost in Hollywood" is a re-recording of a song Bonnet recorded during his tenure with Rainbow.
Document 15: Ronnie James Dio: Ronald James Padavona (July 10, 1942May 16, 2010), better known by his stage name Ronnie James Dio, was an American singer, songwriter, and musician. He fronted and/or founded numerous groups including Elf, Rainbow, Black Sabbath, Dio, and Heaven & Hell. He is credited with popularizing the "metal horns" hand gesture in metal culture and was known for his medieval-themed lyrics. Dio possessed a powerful versatile vocal range capable of singing both hard rock and lighter ballads.
ground_truth: rock singer