Chef standalone install with existing org and user

I already have an existing org and user and am trying to configure a chef standalone server inside my on premise test environment. How do I update the chef server so that it can use these existing users and org?

I’m not sure I understand what you are looking for but it sounds like you’re trying to connect two chef-servers via some sort of Fedaration, i.e. sharing users and orgs between chef-servers. That is not presently possible if that is what you are after.