During the sites self-registration process, I have only come across the ability to create a portal user that creates both a contact and a user synchronously.  I would like to be able to create a portal user using an existing contact.  I tried setting the contact id on the user object before I called createPortalUser, but it still created a new contact.  We are trying to eliminate the possibility of duplicate contacts.

During the sites self-registration process, I have only come across the ability to create a portal user that creates both a contact and a user synchronously.  I would like to be able to create a portal user using an existing contact.  I tried setting the contact id on the user object before I called createPortalUser, but it still created a new contact.  We are trying to eliminate the possibility of duplicate contacts.