Specifically in California? I've looked online and can't find what i'm looking for and hoping someone here may know. We have an ongoing situation with our upstairs neighbor renting out a bedroom to her relatives. They have all been under 20 and we have had issues with them being loud past midnight and beyond. We have tried resolving it with them but the main and only person who is on the lease is hardly there. She also seems to let family and friends use her apartment when she is not there either. My question is, can she have people living up there that are not on the lease? Can she have friends and family use her apartment when she is not around? I'm assuming no, but want to know for sure what kind of leverage I have when I make a complaint to the landlord. I'm trying to arrange a meeting with him and the other tenant to work it out. Thanks for any advice, I hope it makes sense.