Pre-Owned Faking It (Paperback 9780312983826) by Jennifer Crusie

LOVE AND DECEPTION HAVE A LOT IN COMMON.
Meet the Goodnights, a respectable family who run a respectable art gallery-and have for generations. There's Gwen, the matriarch who likes to escape reality, Eve the oldest daughter who has a slight identity problem (she has two), Nadine, the granddaughter who's ready to follow in the family footsteps as soon as she can find a set that isn't leading off a cliff. And lastly, Matilda, the youngest daughter, has inherited the secret locked down in the basement of the Goodnight Gallery, the secret she's willing to do almost anything to keep, even break into a house in the dead of night to steal back her past.

THE RISKS ARE INTOXICATING.
Meet the Dempseys, or at least meet Davy, a reformed con man who's just been ripped off for a cool three million by his financial manager, who then gallantly turned it over to Clea Lewis, the most beautiful sociopath Davy ever slept with. Davy wants the money back, but more than that he'll do anything to keep Clea from winning, including break into her house in the dead of night to steal back his future.

AND IF YOU'RE REALLY GOOD AT THEM, THEY BOTH PAY OFF.
One collision in a closet later, Tilda and Davy reluctantly join forces to combat Clea, suspicious art collectors, a disgruntled heir, and an exasperated hitman, all the while coping with a mutant dachshund, a juke box stuck in the sixties, questionable sex, and the growing realization that they can't turn their backs on the people they were meant to be...or the people they were born to love.