When her tall, dark, delicious husband joins their three kids in calling her "Mom," Karol Simons has an identity crisis. Sure she loves the pint-size trio, but what's happened to her dreams of writing a novel? Determined to have it all, she turns to her neighbor for help.

Dyanne Thornton is thrilled to stand in as Mom for three weeks so Karol can write. Bursting with baby fever, the career-woman trades her glamorous clothes and four-inch heels for the playground and potty training. She hopes to convince her reluctant husband they should start a family of their own, right away.

Everyone's in for some big surprises.…