Question about Combo Boxes in Microsoft Access

I have a form where the user selects a product type from a combo box and what they select is used to narrow down the selection in the opportunity combo box.  Then when they click on create a quote, the data from the opportunity combo box is appended into a table and that record is displayed on a different form.

I would like to give user another option, instead of selecting a value in the product type combo box box they can enter a key number in the opportunity ref no text field.  Once they do that, I would like the opportunity name combo box to automatically populate with that record and the value to be displayed.  

Marilyn
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