Hi TomW
There are two options I see for you. You could do as Nebo did and create a custom field and populate it. This will require some customization to edit the screens to add the new field to the screen and the grid. Also, depending on how the Leads are coming into the system, some additional work may also be needed.
Another option is to utilize our Tags Feature. With tags, you can put multiple labels onto the same contact. This is more of a stock solution, as the Tags field is included on our stock Leads and Contact List screen and Customer and Contact List screens. As long as the tags are created, you can also import and update existing contacts with you new tags. See our Help Center article on Importing and Exporting for additional information.
If you wish to go ahead with the customization option and need some assistance, our Method Consultants are available to you. Let me know if you'd like talk to a consultant and I can get the ball rolling.
Hope this helps.
- Adam