The main use case for groups is to easily move buildings with multiple geometries without losing their relationship to other geometries in the building.
To move the group, select any geometry within the group.
All geometries are selected when one group geometry is clicked!
Move as you would a single geometry, including using Basepoint Move or Basepoint Rotate
You can also manipulate the entire group by stretching or rotating the bounding box. All group elements are scaled or stretched to the same amount.