Step-Parent Relationship Cheat?
My sim had a daughter and then married a woman that wasn't her mom. When my sim married her, she and his daughter originally had the "step-parent/step-child" relationship, but it's somehow disappeare...
Forum Discussion
I'm not sure it's possible. Sims only seems to take into account blood relations. You should be able to test this by making the step-mother her actual mother by setting the relationship bit. See if that cools off the romance with the girl's cousin. If it does, then I'm not sure what you can do. You can leave it like that, or wait for EA to add marriage relations to the romance restrictions.
