I have several fields that are on our fulfillments that need to be manually added to our invoices.  I can't seem to automate their population the obvious way, by looking at the "created from" fields, since even though you bill from the fulfillment, the invoice is created from the sales order, and these fields aren't on the SO, they're on the IF. 

I don't do scripts and I can sometimes manage a workflow.

If I do a saved search looking at both the invoices and fulfillments, then we can't direct line edit either... which would've been easier than 3 hunt, cut & pastes when creating each invoice.