How to put two or more (multiple) header rows in the invoice items table

How to put two or more (multiple) header rows in the invoice items table

Is it possible to put two header rows next to each other in the invoice item table on the invoice? We have headers that need to be bullet-pointed. I considered making them invoice items with zero QTY, AMOUNTS, etc. but a zero shows up in the numeric columns.

Has anyone thought of a workaround?

Invoice item QTY RATE AMOUNT
Invoice Header 1 
Invoice Header 2
Invoice Header 3
Invoice item QTY RATE AMOUNT