Allergen Verification with Multiple Allergens - Does it Require Testing All Allergens?

We produce multiple items that contain different allergens. During Allergen Changeovers from an item that contains (1) Wheat (2) Dairy, and (3) Egg to an item that only contains (4) Soy, is it industry standard to test for all three (Wheat, Dairy and Egg) allergens on equipment surfaces after cleaning? Should testing the predominant ingredient, or just one allergen, within the item satisfy all allergens have been removed?

(One could argue certain proteins are harder to remove than others and its always best practice to make sure all allergenic proteins have been removed, unless you have your own scientific backed study to show for.)

If you validate your cleaning activities to be effective (annually with an accredited third-party lab, where all 3 allergen swab results are negative), would the following statement be acceptable to a "seasoned" SQF Auditor --  "We validated our cleaning activities to be effective at removing all three allergens from the same item (a year ago), and the machine surface today tested negative for (1) Wheat, therefor we are confident all other allergens were effectively removed from machine surfaces today, based on our annual validation of our cleaning activities which all three allergens were effectively removed after cleaning."

Open to all thoughts, advice and direction. Thank you.

Nope, you cannot use that statement

Not all allergens behave the same, you need to swab for each one

You can use allersnap swabs from hygiena  during changeovers. The swab detects allergen presence on the surface, so you don't need to test individual allergen. You can still continue annual validation to external lab.

The certifying body for our allergen free products accepts the logic that a test for one allergen can indicate the completeness of a cleaning procedure for other allergens.

We are performing redundant sets of tests for a wide array of allergens, but we do not test every single piece of equipment for every single allergen considered.  A soy test on a dicer, a wheat/gluten test on a xray, and a milk test on a conveyor belt, with all three pieces of equipment in the same room for the same wash cycle are adequate to claim that all three allergens have been removed from all three pieces of equipment during that wash cycle.

During a production run of a certified product we're performing around a hundred allergen tests as the product progresses through various intermediate stages.  If it was a full battery of tests on each piece of equipment it would be over a thousand tests, and far beyond economically inviable.

We have egg, soy, and tree nuts that vary from product to product. I'm testing for milk, which is in every product (validate these three and milk annually) and defending it using a research paper that compared various allergens, showing that if cleaned improperly how often they were present. Milk was the most likely to be present if not properly cleaned and, with it in all products, most likely to be present. I have my annual audit coming up, hope that I can justify the practice, too late to turn back for this audit.