A new control

 I was asked to explain how else a notebook could vanish if not by notebooking money to the partner of the person, then how?

This is most easily explained by comparing it to a trojan virus. A trojan virus imitates a piece of software that exists on the host computer and then begins removing system files that are critical to the computers function and how this relates to notebooking is simple:

Much like a Russian nesting doll they took their own software and placed it inside of another software. Then, when they  notebooked someone it appeared as though they were notebooked by the software that contained their own software. This in turn made notebooks disappear out of the spreadsheet because you're taking a partner and notebooking money using the partner's software out of the holder's software which makes previous notebooks disappear. It's kind of like the movie with Ashton Kutcher The Butterfly Effect one ripple can cause unforeseen consequences.