So, I've tried to search the forums and the internet and nothing helps.

It's about the nannies. My question is, can you outright move a nanny into a household without screwing up the game? Is a nanny considered a safe NPC?

In Sims 2, we had a long list of what-not-to-do's and a list of safe and unsafe NPC's because let's face it, as great as it was, it was very finicky. So, now, I'm a bit paranoid of just doing simple things and such because I've had to reinstall Sims 2 and restart the entire game and years of progress at least a handful of times.

Is there a list of safe / unsafe NPC's and a list of what-not-to-do's that I'm not finding for Sims 4 that we had for Sims 2? Are there many restrictions? I have heard that Sims 4 is a bit more stable. Is that true?