If you use a calculation field to produce lines 2 and 3 for each record, you can define a calcuation field that is empty when FileD and Comment are empty respectively. Then you can set slide up/also resize enclosing part to remove the blank space when you print or preview the report. The sliding will not be visible in browse mode.
Here's a sample calcluation for the FileD line:
If ( Not IsEmpty ( FileD ) ; "Filed: " ; "" )