So I have always managed my family. However, for this upcoming trip, I want to be able to have some of my kids manage themselves since they are going with a school group. I know better than to create a whole new person for them, but is there a way they can set up their own MDE?
They need to set up their own MDE first. Then in your F&F list, you need to click their name, then, under Share Plans, click Send Email (to the email address they used to create their MDE account) or Scan Linking Code (if they're physically close enough to you for you to scan the code in their MDE account). That will link their new MDE to your F&F list and remove them from your management (although you can still plan for them and share plans with them in future).