This is from the page explaining neighborhood stories:
"It's also worth noting that these options will never be available to perform on another member of your active household, even if you meet the relationship requirements to use them on NPCs."
I really have to question why they went with "from the active family" rather than households marked as "played". Not to mention anyone in a romantic relationship with households marked as played. I wouldn't want a simple conversation to get any played household pregnant, even if it's not the household that is currently active. Nor would I want it to cause an active sim to get pregnant simply because she had a conversation with her SO who has not yet joined the active household.
They really need to give us more options to toggle more sims/households off for this feature. Just mho. I'd like to be able to use it, but not quite as broadly as it currently reaches. They need to take a page out of Deaderpool's playbook and let us set flags on households and Sims for who can and cannot be impacted by neighborhood stories.