Los Angeles - Tenant's "guest" for an extended period of time

[Zhenya Levchenko]

I have a duplex in a rent controlled part of Los Angeles. I live in one unit and rent the other. My tenant recently broke up with her boyfriend (who WAS on the lease but got removed through and addendum) and is now dating another guy. She is a good tenant and pays on time. She can afford to pay on her own, but Los Angeles rent rates are very high even for Boyle Heights where I am.

She previously mentioned a possibility of a roommate and we agreed she would let me know if there is a need. Now there is a new guy who she said is "staying there for the time being". what are the consequences of me NOT having him on the lease?

If she pays the bills and is responsible for the property, I am okay with having just her on the lease. She is an up and coming musician (known) and I feel comfortable with her being solely responsible. What I don't want is: adding some guy onto the lease, them breaking up when the lease is up and they are on a month-to-month, her leaving and me being stuck with a potentially bad tenant. In Los Angeles, this could be a nightmare.

I know that the rule of thumb is to have every occupant documented, but what about in LA? If I don't accept rent from that guy and have no documents, he has no rights to the rental. Are there any negative consequences to this? Can I simply list him and an occupant if I have to?

Thank you for your input in advance.