C/4HANA Sales & Service (aka C4C) allows you to modify the ID mapping for different entities such as Materials, Business Partners, etc.  This is usually accessed in Work Center  Administrator->ID Mapping for Integration.

If you are using the ID mapping from Microsoft Excel  (top left) feature to import your updated ID mapping entries, it will bring up a downloaded Excel sheet as follows.  This is an active Excel file that can login into C4C and allows to save updated entries via API into C4C.

Note – first be sure to click on the Menu Heading “SAP CLOUD FOR CUSTOMER” (green bar), and Logon.

After log on, you should be able to click on cell C4 and select Lookup button.  At the popup, you can click Search button and see a list of BOs to select from:

If you get the error that NOTHING appears for cells C4 or C5, it may be that your SAP Add-in for Excel is outdated, and needs to be updated.

If this is the case, first delete the Excel Add-In as follows:

1. 1. In Excel, click the File tab, click Options, and then click the Add-Ins category.

1. 1. In the Manage box (way down at bottom), click COM Add-ins, and then click Go.

      The COM Add-Ins dialog box appears.

1. 1. In the Add-Ins available box, clear the check box next to the SAP Add-in for Microsoft Excel add-in that you want to remove, and then click Remove.

Then you have to install the latest from C4C screen.

1. 1. In C4C screen, simply click on Downloads link in the upper right of your C4C screen:

2.  Click on Add-In for Microsoft Excel, and it will install the latest version.