Connecting two tables by multiple fields

Hi!

I have 3 tables. Country table has an active relationship with Sales Documents and Billing Documents, and is filtering the Country column in these tables.

I need to connect Sales Documents and Billing Documents:

Sales Documents[Country for Billing] -> Billing Documents[Country]

Sales Documents[City for Billing] -> Billing Documents[City]

Sales Documents[Billing Type] -> Billing Documents[Billing Type]

I want to count the billing documents for each combination of colums in Sales Documents Table.

Here are the tables:

And my desired output:

Can somebody help me with this? 

I can't create even one active relationship between Sales and Billing tables, because they both have already an active relationship with the Country table, which I can't delete. 

Thanks in advance! 🙂