Sum Values in Matrix based in another value in that matrix

Hi TomMartens , 
appologies, it's been a few days until I had capacity  to look at your reply.
Unfortunately not quite the result I am hoping for. 
Your big table on the right shows multiple forecast versions per week, therefore your result in the left table is for Forecasted Value is the sum of all those weeks, even the ones that I didn't want to consider.   

Your right table should look like this 

So that the sum of ForecastedValue, per (Used)ForecastVersion only considers the weeks where that version was 'active'. 
Based on my example, 

F1 2025 = 4026

F2 2025 = 4442
and so on...

Thanks
Marius