How can I print multiple DFR's at once?

That seems to be the fix, but it always wants to plug in today’s date and run a blank report. I went into the report designer and changed the schema setting to allow null in the date field too. Before I did that, you could see today’s date briefly reappear on the parameters screen. Once I allowed null, it seemed to remain blank but still wouldn’t look at the additional filters and display multiple reports. When I use a valid single day from last year, the correct report is displayed so I know it’s working right. Is there no way to ever display or print dozens of old DRF’s at once? 

Check in the report parameters (in Report Designer).  If there’s condition that the DFR Date must equal the date parameter or that the DFR RefNbr must equal the DFR parameter that could be the issue.  You may need to look at editing the report filter options to allow for one or both of these to be blank.