Luck of the Devil (Speak of the Devil, Book 1) by Patricia Eimer

Being the youngest daughter of the Devil isn't all it's cracked up to be. The days of teenage rebellion and vows of chastity made just to tick off her father are over, and now all Faith Bettincourt wants is a nice, quiet life. Unfortunately, thanks to the unexpected arrival of her demonically-downsized sister, a ditzy succubus roommate, and dear old Dad himself, Faith's plans for a relaxing vacation spent watching reruns go up in flames.

Now it's all Faith can do to keep the family reunion from Hell (literally) under wraps, and the angelically-inclined hottie across the hall from realizing there's something weird about his neighbor. And, thankfully, it's working. Until an angelic stalker shows up in a bid to steal her powers and take over the world.

Forget watching reruns. With the way things are going, Faith will need the luck of the Devil just to survive until Monday.