It looks like the list of switches is incomplete: There is also a switch /Edit. It "opens the specified files in a running instance of this application. If there are no running instances, it will start a new instance with a simplified window layout." Unfortunately it also looks like this does not work together with the "/Command Edit.Goto" option: If I use it with /Edit, the "/Command Edit.Goto" is ignored. And if I use only the latter, I get a new window each time :(