Add or Update logic for Item Master

Hi,

I am reading a large list of Item Master data from an Excel file using DI API, and want to upload those items into SAP B1.

There is a possibility that some of the items might already exist in company database (either the user might have created or they may have got created in one of the previous runs of my tool)

I want to detect such items and call the Update method on them automatically (similar to DTW Add or Update behaviour).

What is the recommended way? There is no Item Code in the Excel file.

Thanks.