Once again, I highly recommend against using the first visual solution I was able to create. I've created a 2nd matrix in the report that's a better way of working with the data, though still not as good as starting to record the source or adding in 3rd party orders to the original moving forward.
Ok, so I was looking through your data, and I think I figured out how you have it set up. First of all, an unrelated tip, you should select your Date table, and mark it as a date table in the Modeling tab.
So correct me if I'm mistaken, but what you want is to first figure out how much stuff has Location = Warehouse, and then subtract quantities from Production A and Production B that have a destination of Warehouse.
That was the easy part. Trying to get it formatted in a table like you wanted got much harder. Since it isn't categorized data like Location, you can't use it as a row in a matrix. A few solutions to that issue include:
You could add rows to your data where [Location]=3rd Party and [Destination]=Warehouse so that you can group it properly. This is a bad option, since it requires a lot of manual editing.
You could create a calculated table that calculates each year of A, B, & 3rd party sourcing.
The best option would be to add a Source column to your future data. That would solve this issue immediately and cleanly.
Another bad option is to play with table formatting to end up with something like this: I made this monstrosity by swapping the Rows and columns of your matrix, and then creating another measure that just all products and is filtered by company like your original matrix. After that, I created 2 tables of data seperated by year, turning off word wrap, shrinking the year columns to nothing, and positioning the 3rd party table and total table to line up with the matrix. It technically displays all the info you want, but will fail if there's a time period with no 3rd party products, since the years won't line up. Trying to maintain this setup will be cumbersome at best. I seriously do NOT recommend doing this.