Limit planner access

As of now, a planner Plan is tied to a Office 365 group, which means that everyone in this group (team) can access it! Either you create teams based on who will have access to the plan or you use a website tab to paste the url from another plan into any channels of a team used today. Only the members in that team that also are members of that other teams plan will have access.

You can create sub plans in a team and add different ones in the channels but these are indeed accessible to all members

Adam