We had been using an older version of PDFC, dated prior to March 2017. It had a save button on the menu bar - we could use it to save a combined file (we save directly to postscript format). Our version was inadvertently upgraded, now no save button on the menu bar. Is there an internal setting for PDFC to have the save button on the menu bar, or was it version specific? 'Printing' as postscript file does not produce the same result.
Do you remember the exact version you have used in the past?
If you want to 'access/retrieve' the PS file you may want to try this workaround: Please run your print, but do not finish the conversion with PDFCreator. Instead go to the spool folder: Users > User name > AppData > Local > Temp > PDFCreator
However, I did not manage to 'get hold' of the PS file when merging two or more documents.