I see. So to restate: this circles back to @mlucas point that Drivers usually coincide with/are connected to the previous and/or next Signpost/PSR beat.
So to use your example, maybe this…
…gets so extreme and controversial that the university makes national news, which brings it to the attention of Obama’s campaign manager, who then Decides to come and help. If one were using the PSR, this decision could be connected to/inspired by those variations (I can’t think of any good examples now…) in addition to whatever everyone is Doing in the second signpost.
Is that kind of what you meant?