I use a couple of 430EXIIs for outdoor portraiture. I also have one 580EX and one 580EXII.

I typically use a white umbrella to shoot through. I trigger the flashes with the TTL Pocketwizards. I typically flank the person(s) with an umbrella/flash.

I would like to add a flash bracket, to add more flashes, for greater light output.

Can I use the 580s as the main flash (triggered by the PW), then set the 430s as slaves, while they are installed so close on a bracket?

Interfit makes a 3 flash bracket, and it will hold an umbrella.

Please give me some ideas and suggestions. Thanks.