@bms953 superseding a core features use lie that is a bad idea;. it will break phasing and wreak havoc on area calculations. Options would be a much better way to do what you are trying to do within the current functionality of Revit(R22/23). In this case I agree with @casquatch for greater separation - more like "area" plans- dedicated to a particular purpose. Being able to "zone" rooms together would be another option (I.e. https://forums.autodesk.com/t5/revit-ideas/eliminate-rooms-and-use-spaces/idc-p/11523676#M47606) which would allow more data (visible by discipline or "coordinate" views) to associate with those areas VIA Key schedule or some similar transparent 'grouping' means; but not groups or assemblies- similar to the idea of them.