Thanks for the reply.
The slave cell I posted looks like it allows a Sony flash to be mounted on top of it (with the ISO hotshoe or screw mount below)
I was thinking that I usually have one flash 'in sight', but it's the occasion where I would like to trigger a flash that is out of sight. (i.e. in the car shot, having a flash some distance away with a gel pointing up to give a nice backdrop.)
I can connect my Cactus to the camera PC sync socket (to fire the remote flash 'radio' wirelessly), but use manual flash on the camera to fire my second local flash via the slave trigger when set to manual flash (thanks for that!)
I was thinking what I was trying to do before when I made that incorrect statement about Pre-Flash, and it was trying to use the Sony/Minolta 'wireless function' as well as Strobes triggered via internal slave triggers.
Sorry back to my original thought...
I was thinking about getting a second FS-1200 and a second Cactus trigger, but the prices of FS-1200 seem to be rising (and going for very silly money!) and it did seem cheaper (and easier longer term) - just to sell one of my 56's for a few triggers and a Nikon/Canon/Metz/anything-powerful-with-a-ISO-hotshoe..... so I'd have one flash to use in full ADI/Pre-TTL mode and the two flashes to use tirelessly in full manual mode when I want to be more creative.
I am a bit of a techno head, so although frustrated with the Sony/Minolta flash system - I do like the challenge of trying to find the right bits to get a workable and flexable system.
Anyway, thanks for the info. BTW, are those Metz 'Hammerheads' easy to mount on a tripod with an umbrella?