Ann: Becoming a substantial holder, page-15

Because there are multiple related parties who need to disclose in that single document. It's really that simple.

Put another way, beware of the trap of simply adding all the numbers in the table together and trying to reconcile it against the headline holding. When a relatively 'vanilla' holder reports, the simply summing the parts might work. However, when a complex holder reports, with numerous related entities that each need to disclose for essentially the same holding element, then simply adding them all up will result in double-counting.