1. Create new row/s for each user entered in Users column in SharePoint list item if the record does not exist in Excel table
  2. Update existing row/s based on the SharePoint list item modifications if the record exist in Excel table

Solution

SharePoint List

sharepoint-test-list

Excel Sheet with Table

excel-initial

Flow attached to SharePoint List with Complete a custom action for the selected item template

flow-add-or-update-excel-2

Flow First Time Execution

excel-first-run

Flow Second Time Execution with list item modifications

sharepoint-test-list-item-updated

excel-update-run