Can you have a set amount of lines appear on an invoice specification printout regardless of how many lines are actually in the invoice?

We have a request to generate an invoice and if there is one line or 10 lines on the invoice the resulting invoice printout they want to show 14 detail lines.

So for example if there were 10 detail lines on the invoice they still want to show 14 detail lines so the bottom 4 would be blank.

Hope this makes sense.

Thanks in advance.