The business model is to only apply the pain and inconvenience the the original group. Those people are already massively ticked off with you, so there's not much you can do to help. If you start bumping people off other flights, you just add to the number of people frantically writing to lawyers. You'll see it frequently with widespread weather cancellations, you don't keep bumping the problem down the schedule, you just draw a line and accept you're going to have a a group of angry passengers, but at least it's a controlled group.