Cheat to add Sims to household?

This comment is years late, but i think if you returned to the university (via enroll) you could find her and use "testingcheatsenabled true" cheat, then shift click the girl and add her to your household and then return home.

I wanted to see if i could keep a zombie sim in my household so i added it to my household (it didn't stay a zombie) and when i returned home that person was still in my family's household.