Adding Non-Tenant Codes to GCP in Third Party mode is easy from the Non-Tenant button.
This will bring up the Non Tenant Codes window. Click the + sign to add a new key code. Enter the Name and key code on the left hand side. The name should not include any special characters such as ” or ‘.
On the right side please fill in the Access Rights, Keypad Zone and Time Zone for this non-tenant. Click Save and Close to save the key code.