We already support this. In terms of the GUI interface might mean a little mucking around but just listing multiple profiles and simulating them all (Be sure to disable optimal_raid) would what you want.
That's pretty much how the Raid_T13H.simc profiles work. We create a profile that lists all our various specs but for the purposes of the Sim they're just all players in the same raid group attacking the same target. We do by default keep on optimal_raid=1 which just ensures that all the raid buffs are covered even if the raid is missing that particular buff. Turning off the optimal_raid=1 would ensure each class cast its buffs etc. instead.
I want to simulate all the dps in my guild (with "optimal_raid=1").
The way I do it now is like this: from Simulationcraft/Import I navigate to each person's armory, import it, append the generated text into a separate file. Then I simulate the file and I get a result html like the one for Raid_T14H.simc.
Can I do it in a more efficient way? For instance, if I want to simulate my raid a month from now, I'll have to re-import manually everyone. Can I create a file with the links to the armory profiles and make Simulationcraft import all those chars and then simulate them?