My wife and I have a OneNote list for Things To Do and another one for Groceries. Both shared in Family Room. OneNote has check boxes that are handy for these purposes. It works great for us. (We don't use the Outlook calendar in Family Room. We prefer to just send Invites to each other, on each of our personal calendars.).
If you manage to do so, please do not hesitate on contactingThe Outlook calendar has Tasks which are similar to To Do. I would think it would work in Family Room..