Selecting pieces of exploded object

ok, it is made clear to me that left->right / right->left selection is not a ‘thing’ in blender.So I would like to ask more experienced users how they would go about solving this problem:

I have a fractured model imported from another application: in the image I have a window section model which is supposed to be 8 pieces but each one of them is ‘broken’ into tenths more.
My intention is to select the pieces of each object and press ctrl+j to merge them.

the problem is that without right-> left selection, I have to select the pieces one by one because if I use rectangle selection all the neighboring parts will be selected as well…
e.g. the selected object in the image is a single glass pane that was ‘broken’ into 12 small pieces which I had to select one by one and I want to avoid doing the same thing for the rest of the objects.

any solutions?

In edit mode hover over your mouse to the part you want to select and hit L. This selects whole mesh that is connected to it. (Also check its options at bottom left after the operation)

that’s the problem:
they are separate objects! (each bevel of the glass has been imported as a separate entity)
this operation has to be done on object level!
edit:
(btw, don’t bother too much. I have already solved this problem by selecting the pieces ‘manually’ one by one. the reason I keep searching this is just to find the best practice for similar cases in the future)
also: I see now why 2.8 cannot be used yet for production: a lot of features (like importers) are still missing…

Then selecting objects from outliner could be useful.