The function of the Group/Ungroup feature is a quick and dirty way to create one-off Footprints in the PCB Editor or Symbols in the Schematic Editor or to modify those that are already in the PCB or Schematic but which are unlikely to ever be required again outside of them, in some way. It also allows you to Ungroup Symbols in an existing Schematic and Footprints in an existing PCB so that they can be easily copied and pasted into the Schematic Symbol or PCB Footprint Editor as a shortcut to creating a new library part. PCB Footprints and Schematic Symbols created in their dedicated Editors are automatically added to the public EasyEDA library so there is no need for this function in the Footprint Editor.