CiviCRM Community Forums (archive)

I've been trying to think of a good way to do this and hoping someone on the forum can help.

I'm using CiviCRM to manage a group of fraternity contacts for a metro area.  The membership list can come from two places - the national fraternity and the university the alumnus attended.  It's advantageous to have information from both because the fraternity may have contact information the university doesn't, and vice versa. 

I have the fraternity ID set as the external ID, so I can import changes very easily by matching on that field.  I'd like to do the same for the university ID.  I could create a custom field for this, but I'm not seeing how to designate it at as a "matching" field for an import.  Using email as a unique identifier also doesn't work well because most of the contacts I want to import don't have email addresses in my records.

Does anyone have a suggestion of how to solve this scenario?  Thanks in advance for your help.