You need to use the GUIDs for selection and tracking for this to work. Write the GUIDs out when you export to excel, and then have the coworker do their stuff (not modifying the GUID values), and use the GUID to select the items in the correct order when you go to push the values from excel back into Revit.
I believe Archi-Lab has a package for the selection, referring only to ID in the name (Select.ByID maybe?).