A group should work like this:
select a couple of objects and make a group. A point helper appears and those objects gets linked to that point helper (it shouldn't be a point helper but something similar and unique, a null of some sort). The null works as the pivot of the group and dosn't shift if you move an item in the group.
If you select any object in that group you select everything in the group. Unless you open it. That works like the current group.
Instancing a group and adding an object to it updates all the groups. Any transform made to an object in an instanced group applies to all the corresponding objects in the other instances.
Lets say you have made a group of a lightpost. You have made 50 instances of that and you find yourself want to add a light to that group. With this solution you would just add a light to one group and place it where it needs to be and all other instances will be updated and ready to render.
There, simple and effective!
Yes, rework groups or containers. I just want it simple.
Yes, you can get the transform controllers to be instanced but you can't add an object to an instanced group and that object appears in each group. Right?
That would be a great feature to have. The container workflow isn't worth the hassle right now. In my opinion.
AdminMartin Breidt (Admin, Autodesk) commented
Agreed that Container workflow leaves a lot to be desired, but in principle, they would precisely do what you suggest. So the question is whether your request should rather be about improving Containers?
Just as a note: If you copy+paste-instance the Transform controller of each node in the master group to the nodes in the instanced copy, you can get what you describe. This could make for a nice MAXScript tool...
Nevermind the shifting pivot thing... Focus on the instancing and the ability to add objects to instanced groups that updates all instanced groups.
Containers feels too complex and buggy for this simple task. This should be as simple as I describe it above.