Microsoft has announced the ability of the Planner web app to create multiple plans for an Office 365 group. This is a useful feature that Teams and SharePoint Online (the Planner web part) can already do, but some extra work was needed to break the connection between a plan and a group, and that's what Multiplan means. Or it means a spreadsheet. Or something...
https://www.petri.com/planner-does-multiplan
