[jvriezen]

One thing that I've missed in this entire discussion is any mention of actually communicating with Z and learning more about the changes and his reasons/motivations.

A simple email or face to face discussion that starts with: "I'm very happy that even with the loss of our previous lead mentors, the team will continue with new leadership. I appreciate that you are willing to step up to the plate! I saw the new schedule for this year and I see that it is very different compared to previous years. I'm curious to discuss why some things are changing so that I can better understand your point of view on things and would like to contribute in any way I can to help make sure this team stays healthy, vibrant and continues to serve students long into the future."

Notice the lack of negativity in the above? Maybe Z made the schedule like that because he's 'in over his head' and doesn't think he has the bandwidth or the expertise to continue certain aspects of the team in the same way as before. From what is in this thread, we don't know what's in Z's head beyond one schedule he posted. Communication is key here. Maybe you and the other students need to proactively recruit other new mentors who are willing to take on the tasks that Z has not addressed.