Can't create correct relationship

I've spent hours creating a DB to track inventory for a convenience store via purchase invoices. Once completed everything was working the way it should except I realized it was too time consuming when it came to entering Product information because 1)My Product ID's were different from my supplier ID #'s 2) My Product Descriptions were different from my suppliers 3) I purchase the same products from several different supplies . What I now want to do is to be able to enter the Product Id's of ABC Company or EFG Company or XYZ Company and have it always bring up My Product ID #. I've tried a few different ways but can't get it to work & I'm now becoming too confused. Can anyone shed some light on what it is I should be doing here? I've included my stripped down file to show what I'm already using. Any help would be appreciated Thanks

DR_Sample_Inventory_DB.zip