sending messages to specific Client with node-ipc

Question

I have an electron app where different clients communicate with a server over a Network using node-ipc.

As long as the client connects to the server first it is no problem to answer that specific client. According to the docs I have on the Server:

NodeIpc.serveNet(
    function () {
NodeIpc.server.on(
            'Client.message',
            function (data, socket) {
                NodeIpc.log('got a message from', (data.id), (data.message));
                NodeIpc.server.emit(
                    socket,
                    'ServerData',
                    {
                        message: 'have some initial cofiguration data'
                    }
                );
);
    NodeIpc.server.start();
}

and on my Client:

NodeIPC.connectToNet(
'world',
function(){
    NodeIPC.of.world.on(
        'connect',
        function(){
            NodeIPC.log('## connected to world ##', NodeIPC.config.delay);
            NodeIPC.of.world.emit(
                'Client.message',
                {
                    id      : UniqueClientID,
                    message : 'Some information about myself'
                }
            );
        });
});

That works great, but I cannot figure out how to push some additional information to a specific client some time Later. Trying

NodeIpc.server.of['UniqueClientID'].emit(
    'additional Data',
     {
        message: 'some more configuration'
     }
     )
});

and

NodeIpc.server.emit(
     UniqueClientID,
      'additional Data',
       {
           message: 'some more configuration'
       });

do not work. Does anyone know how to send a message to a given client? (of course there is always the possibility to broadcast that message and let the client decide if it's for him, but I would prefer to talk to the directly)