How can an Inbound Integration update Item without knowing Item ID

Summary:

How can an Inbound Integration update Item without knowing Item ID

Content (please ensure you mask any confidential information):

There were a few cases where we need to update an Item via Inbound integration however Item ID is unknown (e.g., external supplier or broker wants to update some information, and of course, they will NOT have GTM Item ID). Instead, inbound messages only have key fields like Part Number (Item Name) or Trading Partner Item Name, etc..

Note some business object has IntSavedQuery element on the xsd, which would help. However that does NOT exist on Item xsd.