The Llanelly marriage may be the Thomas Benjamin Rees b 1891 Llanelly
His parents were Evan Rees and his second wife Lydia nee Evans
The 1901 shows his father as William Evans. Should be his stepfather
1887 marriage shows Evan Rees to Lydia Evans
1900 marriage Lydia Rees to William Evans - possible death for Evan in 1898