[whpalmer4]

I haven't given any thought to how to handle situation 1, but situation 2 seems easy enough to handle. Put a milestone at the end of the chain of tasks in that "after hours" group. You could put a F-S dependency from the group to the milestone so you don't have to worry about individually connecting the tasks to the milestone. Set the end constraint on the milestone to the end of your window of time, and you'll get a violation if you try to put too much in that group.