Merge Joomla account user with Advanced OpenPortal?

If I allow my customer to already have or create their own account on my customer portal on Joomla, how can I allow portal access for them after their email address is already in the joomla system? If an e-mail already exists, SuiteCRM kicks out an error. Is there a way on either system end to enable portal access, after the fact?

You would have to manually update the contact_cstm joomla value in the CRM database and update the sugarcrm id/link in the joomla user table/db.