Blender add-on for managing groups of objects (collection instances).

For Blender  4.2+ (or newer) 

Online Documentation

With GroupPro you can merge objects into one container object in non destructive way (using instances collections).  Features:

• edit any group (collection) instance on scene

• work in recursive way - group, can be created from subgroups, which can be made of subgroups etc. Any subgroup can be edited and saved, with all other instances updated in real-time

• easy mirroring of selected groups (fixes group instance mirror bug in blender)

• change group origin or apply transformations, without destroying positions of other instances placed in scene

• dissolve group (split it into original objects) - with option to create (maya like) empties hierarchy 

• edit material in all group sub-objects in one click (replace, add, assign mat)

• create group proxies (temporary lowpoly version, to speed up viewport)
  

Pros of using group instances:

•  low memory memory usage

•  one click group of object selection

UPDATE: since version 3.x GPro workflow changed - it is using mesh + instance modifier rather than old empty+instance collection.   See video explaining the change.

GroupPro comes with build-in auto-updater - get latest version with one click. See updating  Documentation.

Here is video showing new features GroupPro 2.3

You will get free updates whenever there are new ones.