The only way I have done this is to customize the Grid Edit Report Field Column Properties to add ________ on the end of the Field Names. This means the basic grid gets larger. Since Column Properties are a report-only feature; it only affects that one report, in this case the one used for Grid Edit.
If you are doing the grid editing within a record (embedded report), you most likely won't want the _____ to appear on a regular-embedded report, so consider using one report /Report Link field for Grid Edit-only uses (Edit mode); and the regular embedded report for viewing only. If necessary put your Grid Edit for data-entry into a separate Form.
