How did Charles Rowland and Edwin Payne meet? How did they become ghosts?

References:
The Sandman Vol.2 no.2228 “Season of Mists” (1991)
The Children's Crusade #12 (1993)
The Sandman Presents The Dead Boy Detectives (2001)
Death: At Death’s Door (2003)
The Dead Boy Detectives (2005)
Dead Boy Detectives (2014)
Books of Magic Vol 3 no.2123 (2020)
The Sandman Universe: Dead Boy Detectives (2023)
Dead Patrol S03E03 “Dead Patrol” (2021)

Music:
Song: Suspense Scary Music Music composed and recorded by Oak Studios. Link: • [No Copyright Music] Suspense Scary M... | Creative Commons Attribution ND 4.0
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