A little late to the party but unless I am misunderstanding your request the below Trend Setter SmartApp may do what you are after with the exception that each light will control all the others in turn. You may be able to edit the app to be able to set one as the master of course. It is a really great app and I use it all the time. You also may have to edit the Z-Wave socket DH and add the Light Capability to it. Similar functionality is available with Smart Lighting but this app Actually creates a simulated/virtual device (you could call it ‘Lounge Lights’) which appears in your list of devices and this in turn links all the lights together. Also works with dimmers, colour lights etc.