Blender Market – Qol Tools: Link Widget 1.0: Utilizing linked information (instances also used in different DCCs) can be fiddly and complicated in Blender. Instances are compelling and enable you to deal with massive data sets,.. essential for use in large-scale scenes.
Like many of the Blender workflow options, it offers all the tools you need to deal with instance files; however, it is often not in the most obvious ways or hidden away in a different tab. To make matters more confusing, Blender uses the same term ("Linked") that refers to external links in files (usually also referred to as "references" in other DCCs). (blah blah boring, we know)
However ...
It's a tiny and ever-present device that's low on expenses. It provides an instant indication of whether the current object you've chosen is an instance of it and also tells you the number of instances. It is always located high on your display.
Clicking on it using modifier keys will do many things when you do it to keep you in the loop.
A single click
The disconnects all instances and creates independent objects.
Shift-click
Creates all instances of the object in use.
Alt-click
Select all instances that are connected.
CTRL-click
The selection of all the objects of which they can be considered instances. Not only ones that have identical to the object in use.
It is also possible to select an option available in the preferences for the addon to change this indicator to a monochromatic model for those who prefer not to use a green symbol :)