Portals are based on table occurance, which basically is the realtionship. You would have another relationship matchomg your current table occurance with title = GlobalTitle added and another occurance with title ≠ GlobalTitle added. GlobalTitle would be a global field that you select the title you want to match or not match.
It would help to know the exact relationship you have set up for your portal's relationship. Lacking that, I'll name the two matching fields as PrimaryKey and Foreign key. You could set up this set of tables and relationshps:
Layout'sTable::PrimaryKey = Titles::ForeignKey
Titles::__pkTitleID = Contacts::_fkTitleID
Then you can place a portal to Titles on your layout, but include fields from Contacts in the portal row. Your Title field would be defined in the Titles table, not Contacts.
If the above notation is unfamiliar, see the first post of this thread: Common Forum Relationship and Field Notations Explained