V/63 output billing condition table

I want to trigger a billing doc to output by sold to or payer/sold to.  I can see that my field catalog has KUNAG displayed.  But when I go to add a new condition table, I cannot figure out how to pull KUNAG in as a field to use in the condition table.  This is for email purposes where depending on what the sold to address is, the correct email address will pull from soldto.

Thanks for any assistance.

Susan