Your stepmom has become a widow and in your step-daddy's will he want's you to inherit everything - including your stepmom. Apparently your step-daddy and your stepmom lived in a 24/7 free use relationship, where she was his property. She must now have a new owner, and your step-daddy wants it to be you. He also wanted to make sure the family name lives on, so his last wish was that you'd move into the house, take over your stepmom as your wife and property and breed her over and over again. You can't deny him his last wish, can you?