figure:Index/Match

If you look at my attachment on the Supplier Competitiveness tab, I have highlighted the row yellow I am trying to populate.

Basically under "Supplier 1" I want it to look up in the Overview tab and see what part numbers Supplier 1 bid on. In this case its part numbers 1, 2, and 3. So then I need the formula to go to the Spend tab and sum the Annual Spend for part numbers 1, 2 and 3.

Another example is "Supplier 3" they quoted on all four part numbers in the Overview tab, so I need it to sum the all four part numbers in the Spend Data tab.

I have tried sumifs and I can't get it to work, maybe I'm over thinking it, but I was thinking an Index/Match might help..

Thanks for any help in advance? I attached the file.