Importing messages into F3411 using P3411

I am able to import 'O' messages for purchases and process them to create POs without any issue, but now I want to be able to import a 'D' or 'E' message.  When I try this I get an 'Invalid record' error,  which I suspect is because there the field for 'line number' is not in grid and so when processing the message it fails because it can't find the record.

Is there a way to manually create action messages on the PO line level like this?

Blake