Join / Blending Enquire. Working with missing rows

Hi all,

Can you please share some knowledge Tableau gurus!.

I have the following 2 tables, one with Income, the other one with cost. Both have same key linking fields Fortnight and Project.

Cost table needs to be average it (It comes from a DB with duplicated rows), Income table needs to be sum together.

Income

Cost

As you can see, there are projects at Income table that are missing in Cost table (B1), and vice versa (C1).

I'm trying to report in tableau simple net value of Income - Cost, per project per fortnight.

But because I'm missing rows in each table, only those projects with records in both tables can be represented in Tableau as I want.

Missing B1 and Net for C1 should be (0-20=-20)

I know that if I add dummy rows to both tables I will obtain the result I want, but I'm looking for another way to obtain this.

I guess other solution is to create a single table with all data, and adding 0s to missing values.

Can you please share some light?

Cheers,

Elias