I have the same kind of thing. There are 3 lights in my living room. All lamps, and when you hit on or off, they all function at once. I added a second set of buttons on the orbiter. One for the end table lamp by the TV, one to control the 2 floor lamps at the back of the room. That gives me choices. I also modified the "Showtime" scenario to dim the back floor lamps, and shut off the end table lamp.
But in a pinch, on or off works them all.
Play with your lighting scenarios in the webadmin. You have to add an on and an off button for each light or set of lights you wish to control. But after all of that is completed, should sort it all out for you.