[v8i c#.net] How to connect a specific instance of ustation.exe?

I am connecting to an instance of Microstation and processing the design file as below, but I don't understand how I can connect to a specific instance of Microstation if multiple instances of ustation.exe are running. The code below connects to an instance, but I would like to be able to specify the instance if multiple are running. In the code below I am throwing an exception if I connect to microstation but then discover that multiple ustation.exe are runnning (backwards logic I know). I want to know that 'yes 3 ustation.exe and I have determined that instance 2 is running the dgn that I want so I will connect to it and run'.

bool connected = false;

_app = new BCOM.ApplicationClass();

if(_app == null)

    throw new Exception("Failed to connect to instance of ustation.exe");

if (_app.ActiveDesignFile.IsActive)
{
    Process[] processes = Process.GetProcessesByName("ustation"); 

    if (processes.Length > 1)

    {

        // If I have multiple instances I want to specify who to connect to

        throw new Exception("multiple ustation.exe running. Who did I connect to?");

    }

    connected = true;
}

else

{

    throw new Exception("Connected to ustation.exe but no active design file");

}

return connected;