Yes, on the data structure level it’s always that you enter the linking (e.g. link rooms to volunteers) in one specific place. Then you can build different UI atop of that, e.g. make a separate dedicated form to add assignments like here.
The logic to this is that you don’t want to have multiple sources of truth in your doc, or multiple ways you can enter the same data. That’s why you adopt some convention where you want the inputs to be, and in all other places you’re using formulas to calculate whatever you need from those links. Like that reverse mapping.