The California Secretary of State maintains a registry of Advance Health Care Directives ("AHCD"). The cost of filing a registration form is only $10.
Every unmarried person should consider registering their AHCD. If you are admitted to a hospital, your medical provider can access the registry and contact the agents you have appointed in your AHCD.
The registration form is available at www.sos.ca.gov/ahcdr/forms.htm.