This is something I can do with Illustrator, and that I would like to reproduce with Inkscape 0.91:
I want to scale up several identical objects and I want these objects to remain exactly at the same initial place. When I scale up a selection of objects, they move to the proportion of the scale I indicated, in the larger box of the selection, this is not what I want.
As your objects are identical you should consider making clones for your duplicates.
Make your object (the parent)
Duplicate as required: Edit - Clone - Create Clone (Alt+D)
Scale or otherwise redefine your parent object and watch the children follow suit.
The advantage of this approach is that you don't have to explicitly select all of the instances - they all get updated. Although there is a way to select the parent of a child object I find it more straightforward to create my parent objects off the page for simpler direct selection.
Of course my answer presumes that you want to scale all of your objects - if not you can always start out with clones and unlink those that you don't want affected by subsequent edits to the parent.
The method above seems to be a bit touchy on complex images with a lot of layers.
I don't think it works for text but if you convert text to paths it should work.
Any grouped layers have to be found and ungrouped and I didn't have any luck with selecting all objects in all layers and ungrouping. I think you have to actually get the grouped objects.
Finally, on my image, I had to not check "Apply to each object separately". When I did that it got all weird and nothing was recognizable, or in the correct places. I also had to do my full scale all in one go not in steps.
After the first go it stopped scaling. So if you follow the above steps (which are good) and get weird results, remember the text issue, check for groupings, then try the settings in the Transform tool.