I'm hoping I can put down enough info as I am not the engineer.
My company does autocad drawings for parts for our customers. Often times we actually design the part. After the design, we send via email, but sometimes by fax, a copy of the drawing to the customer for pre production approval.
On several occasions, the customer(s) have taken our drawing(s) and submitted them to our competitors for bid.
So my thought is to put a watermark beneath each drawing before submittal to the customer. My engineer has not been able to make this happen.