portable solution for group photo in a church

Could you suggest a portable flash solution (camera or bracket mounted) to light up a 15~20 group photo in a high-ceiling environment?

self-bump. any suggestion appreciated. or is there no easy solution?

We use a flash on either side of the group mounted to either tripods or cheap light stands and trigger them via pocket wizards. Or you could invest in some portable studio lighting from companies like alien bee.....

Not sure if you have been to strobist or lighting mods, but both are full of great idea's for lighting....

Thanks for your suggestion. Let me take a look at the website.

I think you Sigma has a built in optical slave, the Sunpak on the camera and the Sigma on a stand to one side should work. All would have to be in manual mode. I like the Lumiquest ProMax System and generally put one on each flash when I'm shooting multiple flash.