Just noting this. I just created a user and associated with a PDC organization now in the updated consideration of organizations and potential auth brokering. But, the user domain name is not of the domain of the organization I associated it to.
So, john@abc.com is the user and they are working with foo.com. We want them to be connected to foo.com and it's not a concern around auth brokering because foo.com does not have an association with an IdP, but still wanted to give a heads-up on the instance. I think this could be quite common - essentially someone working for an organization but not OF the organization from a domain name perspective.