Shift-clicking on windows

I have a trigger in BBT such that when I three-finger click on my Magic Mouse, it sends a command-click action. However, I would like to make a conditional trigger where when I three-finger click on an inactive window, it’ll send a shift-click instead. I feel like this is probably possible in the Advanced Conditions trigger config, but I’m a bit lost in there. If it is possible, could anyone point me the right direction?

(Context: I have John Siracusa’s “Front and Center” app installed and set to Classic mode to bring all windows of an app to the front when I click on any window in that app, but it switches back to Modern mode when shift-clicking a window. I would like to be able to invoke that behavior with my mouse alone.)