How to instance groups of objects

[nils.deitmers]

Apologies for the vague question.
This is one that has been bothering me for years, so I'd like to learn if there's a trick I missed...

I find myself working with identical groups of objects all the time, like e.g. robot arms or car engines.
The goal is usually to instanciate the objects, while being able to treat them as one logical unit, but in a non destructive fahion, maintaining all modifers and transforms.

Obviously an almost ideal workflow would be to group the objects, while also instancing the controller. If it wasn't for the one big flaw that you can't add any new objects to a group instance. 
So if you were modeling a robot arm you'd have to regroup and instance it for every screw you decide to add.

Creating a boolean object is another way to do it, but I find this too laggy and cumbersome to work with.
I'll usually create references from my objects and create a boolean from those. So I can continue working on the objects, keeping a turbosmooth modifier above the reference line to enable for preview without affecting the boolean.
This is also not really convenient, since the performance is really bad, even when moving operands with relatively simple geometry.

Is there really no way to work with a bunch of objects that update as a group in real time?

[MartinBeh]

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@nils.deitmers  schrieb:

I realized another "limitation" of the Mesher that I hadn't noticed before. It doesn't just attach meshes, but it performs a boolean operation, so I can't have overlapping geometry, especially if the turbosooth is on the Mesher, since it's probably going to create artefacts or smoothed out areas . This operation may even have sth to do with the display error, since moving one of the objects into overlapping another is a sure way to trigger it. (It can also provoke a crash, as I just found out ^^)

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Absolutely! A hidden Boolean operation between all objects included in the group could also explain the massive slowdown we are seeing as soon as some heavy meshes are in the same group as multiple other (lightweight) meshes. If that turns out to be the case it is basically as if we were using a Boolean compound. 

I will try to look into this some more when I have time again.