SUNSPINNERS 3, 4
This BookClub edition includes the Books 3 and 4 of the Sunspinners novels:
Demonprice, or, Doom of the Penultimate Husband, is the third Sunspinners novel. Elaine's second ex, Nathan, has sold 4/5ths of his soul to the devil and guess who he asks for help. Help! Charley and Elaine end up in the devil's vestibule with no way out.
Demonfire, or, Charm of the Killing Cousin, is Sunspinners novel 4. As though Elaine doesn't have enough relatives at home, a cousin arrives who is willing to sell himself to anyone, including demons.