I'm not seeing where you can order CA death certifs online. However, it appears that you don't need to be a direct relative unless you want a certified copy?
If you cannot obtain an authorized copy under California law, you can obtain an informational copy. An informational copy contains the same information as an authorized copy, but will have a legend across the face with the statement "INFORMATIONAL, NOT A VALID DOCUMENT TO ESTABLISH IDENTITY." Authorized and informational copies are both “certified copies.” http://www.cdph.ca.gov/certlic/birthdeathmar/Pages/Certified...