A Little Less Sixteen Candles.

When two girls set out to rid their city of vampires, they don't count on joining up with others to save people from a fate their own parent suffered. But with the sudden rise in the undead population and the new elite vampire group they take all the help they can get. Until Amanda discovers her sister has been hiding something from her all along, and decides she doesn't want her help anymore.

I suck at these.