I'll explain how I would envision this going, as I've been thinking about the idea, and I wouldn't mind using it.
My debriefings tell you which mission to play next. Or that you've lost. So let's imagine the player has been told to go to Lorric12a.
So the player loads up Lorric12a from the techroom. The briefing in Lorric12a would tell you what the goal is, and tell you that you have some freedom on how to accomplish that goal. You'd click commit, and you and your forces would be around the base or something before the attack, and two or three people would present you with ideas for how to accomplish the goal, and maybe discuss/argue it amongst themselves for a bit, then you'd go to the debriefing and it would say something like...
"The choice is yours. If you want to go with X's plan, go to Lorric12b. If you want to go with Y's plan, go to Lorric12c. If you want to go with Z's plan, go to Lorric12d."