You are seeing all records because basing the layout on the product_DIV_RETURNS does not use that relationship to limit what records show anymore than if you based the layout on Product. The relationship only comes into play in a context where you have both table occurrences in use such as by placing a portal to product_DIV_RETURNS on a Product layout.
a) From a layout based on Product use a script with Go To Related Records to bring up the records that you want. You can refer to product_Div_Returns as your "table" in this script step and specify any layout based on any occurrence of Product to show the resulting found set. This found set can be just those records linked to the current Product record or for all product records in your found set.
b) perform a find on either the product or product_div_returns layout to bring up the desired found set.
Perfect. Thanks a lot!