Hi Robert,

You can use your own User Provider espace.
The only requirement to use BPT & ECT is to have the system entities (User, Role, Group) filled with the Users you manage on your espace.
A common scenario is to when creating Users in you espace, extend the User entity and create a User as well in the system entity. When creating a Department for instance, add a foreign key to the Group system entity and create a hidden Group (eventually named "Department X"). This way, the system entities always have a "non-context aware" vision over your business model and all platform features are able to adapt to your external authentication/authorization logic.