How to add an official USPS address to your new ADU in California

[David Sequeira]

I recently completed an attached ADU Gardena, CA and received my certificate of occupancy by the city. I added the new address to google maps and it was accepted. My tenant is now living there but needs to use the main house address when buying stuff from companies like Walmart, etc... since the 1/2 ADU address does not show up. I look around online and was not able to find a clear way on how to get the address added as an official United States Postal Service address. Does anyone have any experience with this? Any thoughts would be appreciated. Thank you for your help.