Gumroad – Group Pro v2.1.8

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

Features:

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