John, what you could do (and you've already tried it) is to take advantage of using interrupting boundary events. I would see this as make your human tasks that are assigned to the teams (HT-2 and HT-3) signal aware. As boundary events attached directly to a task are not yet supported you need to use sub process for it. It will be simple sub process with only one task and interrupting signal boundary event attached to the sub process. Once a task is completed with Yes response you should throw a signal that corresponds to that boundary event and that will cause abort on the subprocess and its activities.
HTH