Let me describe how I would proceed with this (tried with Checkbox6 and it seems to work).
- Modify the template in Adobe LiveCycle Designer by binding Checkpoint6 to somtehing like $record.us-ids-certification.us-ident.boilerplate-text

- Add <us-ident boilerplate-text="1"/> into data xml file under us-ids-certification tag.
- Process with iText pdfXFA 5.0.0 on java or dotnet (I didn't try with itextsharp but might also work).
This will be the result:
