Excel - dynamic chart with sumif, and data validation list

Hi guys,

i'm trying to get my head around this, hope that some of you could help me, i have checked the net and there is a lot of options but i just cant figure it out :(

Kindly advise.

What i have is a list of products, sales persons and customers,

Each sales persons can do sales for different costumers and different products. I have created a sumif that sums up the sales per product for each sales person, and created a chart, my problem is that new sales persons can be added to the list, so i have made a wider-range then actual, how do i get the chart to not take the empty rows within the chart? is this possible?

I'm open for ideas, and even if the data basis needs to be changed or what have you,

I have tried with creating the offset formula aswell, which works but the blank series still gets added to the chart.

I'm even open to if the chart should be created from VBA, that works for me aswell.

Here is a sample file, to give you guys a idea of how the setup is:
sample-file.xlsx