Using PUGX with multiple simultaneous sub-users

[retosteffen]

I have set up PUGX like this:
abstract User (fosuserbundle)
UserA extends User
UserB extends User

which works well.
Now I would like to be able to have a user be both an UserA and an UserB aka to switch back and forth from being an UserA to UserB but having just one username and password.
Which doesn't work as it's trying to create a new FOSUser when what I want is to "just" create a new "sub-role".
Is there a way to do this?