With GroupPro you can merge objects into one container object in non destructive way (using instances collections).
edit any instances on scene (not just the ‘source’ one, like it works by default, with collection instances)
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, without destroying positions of other instances placed in scene
apply transformations to group (location, rotation, scale)
dissolve group (split it into original objects)
ability to edit linked libraries groups directly in current blend file
edit material in all group sub-objects in one click (replace, add, assign mat)
create group proxies (temporary lowpoly version, to speed up viewport)
This makes working with huge scenes with lots of objects easy and gives all the pros of group instances:
less memory memory usage
easy selection of multiple objects with one click
Here is video tutorial/demo how to use GroupPro (now new videos):
And blenderartist thread with QA:
You will get free updates whenever there are new ones.
Update 2.0.8 and 2.0.9(for Blender 2.8 only)
fixed initialize function
flip – now is aware of previously created copy. It will update its position, instead of creating new instance of flip
Added ability to group collections.
Update 2.0.11 (for Blender 2.8 only fix)
Downloads: pls buy & support the dev!
YOU CAN INSTALL THIS IN BLENDER AND THEN UPDATE IT DIRECTLY FROM BLENDER.