If OAuth is for authorization, then how to register a user?

Question

OAuth

I understand that all users are stored in the oauth_users table. But what if I also need to change the RS database during registration, what should I do then?
Suppose there are 2 roles in the project, worker & manufacturer (should be scalable)
Collection - table, document - row in the table
1. Create a document in the AS database with the fields role="worker" role_id=null
2. Create a document in the RS database, collection thus depends on role. If for example role="worker" then create a document in the workers collection.
3. Change role_id to the id of the document created in step 2.
What should I do in this case?