Link two tables with multiple key values

Hi guys,

I have a problem with the assignment of document receipts from customers to the respective sales employee. I would like to tell the employees which documents are submitted by their customers and how often.

The problem there are two customer numbers. This is due to the business model and cannot be changed.

So in the inbox there can be two different person numbers. I would like to assign these to the Sales Men table via the Contract table.

Does anyone have an idea how this can work? Important to know, what is not shown in the screenshot, is that there is also the case that a customer can have a value at both person numbers.