How do you change a contact type after its created?

In the demo, you have two contact types--volunteer and staff. If one of your volunteers gets hired on as staff, or one of your staff members goes on to a different job but wants to continue to serve as a volunteer? Right now, it seems that your only option would be to create a second contact entry for the same person--and, what, make the first one inactive? disconnect the old one (how?) from the Drupal profile so you can connect the new one? delete the old one and lose its history?

What if a contact has multiple engagements with the organization? I'm looking at Red Hen as an option for a community chorus, which has members, non-member volunteers, donors, supporters (audience), and alumni. Some people shift from one role to another over time. Some interact with the organization in multiple ways at the same time. Right now, it seems as if contact types are one-only/exclusive--no way to change as the contact/constituent's relationship with the organization changes over time, no way to select multiples.