@Karlos
I've tried the setup you describe, but when I start LightWave, it automatically outputs an native mode and my Voodoo/SVGA screen switches off. Even with the TV system running, there's nothing on the monitor.
The only way I can see the LightWave gui is on a 15KHz monitor attached to the A1200 video port. It's Hi-Res Interlaced and impossible to work with.
If I change screen back to the Voodoo one (LeftAmiga+M), there's nothing on the TV screen and the 15KHz screen switches off at the same time.
As commented above, how does the Amiga generate two different screenmodes at the same time? Or does it? I suppose the composite video output isn't a screenmode as such, but simply a separate additional output? How do I get that onto Voodoo when LightWave switches it off? I'm confused by the whole thing!
However, you've probably helped by involving the PC in all this. I can fit the TV card in the PC and direct the Amiga native video to the Composite In connector. I can see how that should work fine. Just means having both machines on together.
Cheers,
JaX