Hey @stevex64 , accomplishing SSO across multiple applications with Auth0 is easy with Auth0 (as long as you use the same Auth0 tenant for all these three applications). After reading your use case, this is my recommendation:
This can be accomplished just by using the same database/databases for all your three applications/websites. This means having the same connection enabled: create a Database Connection on your Auth0 dashboard and enable that connection for all your three applications. You can enable/disable database connections via Connections → Database → click on the database name → Applications tab or alternatively via Applications → click on the application name → Connections tab
By default, if you are using Universal Login, this is automatic and you shouldn’t need to do anything. This means that when using Universal Login, if a user logs in to any of your three applications, that person will be able to SSO to any of the other two applications.
I will leave a couple of resources here for your convenience:
Let me know if all this makes sense and good luck with your integration! 