Command line arguments?

I`m writing some automation software to open specific files from specific location when a barcode is scanned. I have it all working but unfortunately it loads a new instance of coreldraw each time. I can't use DDE since the automation software uses the programs command line arguments and I can't find these through google.

Does anyone know what the argument would be for opening files (in the same instance)?

I`m hoping there is a command line argument for this.