Actually, you don't need to do that. I use this configuration routinely. You seem to have covered all the bases, but I suspect you've missed something small. Here's my checklist:

- UnknowmMember property for dimension set to: Visible

- UnknownMemberName property for dimension is not empty.

- KeyColumns property for the attribute has the property NullProcessing set to: UnknownMember. (Actually, set all the attributes thus way.)

- the KeyColumns property for the attribute points to the field on the dimension table (EMPLOYEE.title_id in your case).

- the NameColumns property for the attribute points to the field on the off board table (TITLE.title_name in your case).

If you still get the error, grab the SQL statements generated during the processing and examine them carefully. Most likely, based on your settings, you have a shortened resultset somehow. This is partially because MSAS only generated inner joins. Often, an unrelated join can filter results unexpectedly. Check your RI!