Can one restrict Picard to a single instance?

I like that Picard accepts files and paths as command-line arguments. Unfortunately, using this feature always opens a new instance of Picard. Is there a way either to restrict Picard to a single instance, or to add files to a running instance from the command line?

As a workaround, I aggregate all directories and then pass them on a single line, but for some scripts this is impractical.