My sister the vampire series by Sienna Mercer

Fangtastic. Egmont, 2009. ISBN 978 114052 43704.
Vampalicious. Egmont, 2009. ISBN 9781405243728.
Love bites. Egmont, 2011. ISBN 9781405256958.
(Ages 10+) Starting with Switched, a book which gave the reader two girls at a school in USA, who worked out that they were twins separated at birth, this series has gained a popular following as the two are so vastly different, one a vampire, and the other, well, normal. Their adventures are very funny, involving and fast paced as the two try to hide the truth from all around them, and attempt to become friends.
In Fangtastic, Olivia and Ivy are getting used to the idea of them being twins, and learning about each other, when the nosey journalist, Serena Starr comes snooping around. Their attempts to put her off the scent meet with hilarious results.
Vampalicious follows, where Olivia and Ivy 's secret has been discovered. Ivy's parents do not believe that Olivia can be trusted not to reveal their secrets and so put her through a series of tests to prove herself.
In Love bites, the pair has gone to Transylvania to meet the scary side of the family, the vampires. Here Ivy is watching over her sister more carefully than usual, because she has become entranced with a very nice boy, but Ivy knows he is a vampire prince and it is coming close to Valentine's Day.
All in this series are easy to read with clever pun filled dialogue, and short snappy adventures overlaid with a large dose of humour.
Fran Knight