Refrigerator. HelloI hope you can help me identify a part. The beverage chiller in the door of my

Question

HelloI hope you can help me identify a part. The beverage chiller in the door of my ARS9167AS has a clear plastic rolling cover, which seats into a white plastic part that also serves as the shelf above. Viewed from the side, there are 3 circular holes to allow freezer air to enter. I need this white plastic part that holds the clear door. What's its number? Can't find it on the usual sites.Thanks!!Elise