Tax Registration Number for First Party Legal Establisments Party Tax Profles LOV

I am trying to record the Tax Registration Number for one of our First Party Legal Establishments. I go to the form (Tax Admin: Parties: Party Tax Profile), query for the First Party Legal Entity in question and click Update Tax Profile.  Then I go to create the Tax Registration tab for the party (click on Create in the Registrations tab).  When I get to the tax registration number field, it is a LOV with no values available.  Where do I set up the number initially so it is available in this field?

I'm attaching a screen shot for clarity though I did blank out the LE details to preserve client confidentiality.