Batman: Prelude to the Wedding is not actually a series in and of itself.
According to the indica #1 should be Batman: Prelude to the Wedding: Nightwing vs. Hush #1.
#2 should be Batman: Prelude to the Wedding: Robin vs. Ra’s al Ghul #1.
#3 should be Batman: Prelude to the Wedding: Batgirl vs. Riddler #1.
#4 should be Batman: Prelude to the Wedding: Red Hood vs. Anarky #1.
#5 should be Batman: Prelude to the Wedding: Harley Quinn vs. Joker #1.
Thanks,
Matt