The aside
is "tangentially related to the content around" it.
Currently, it doesn’t seem to be defined what "around" means exactly. Assuming that it’s (at least) the content of the parent sectioning content element, then this would mean for your examples:
<body> <section> <aside></aside> </section> </body>
Theaside
is related to the content of thesection
.<body> <aside> <section></section> </aside> </body>
Theaside
is related to the content of thebody
(i.e., of the whole document).
So in your case, you’ll probably want to have aside
as descendant of body
(and of no other sectioning content element).
The next thing to decide would be: one aside
with several sub-sections vs. several aside
. I’d go with a separate aside
for each "sidebar block", unless you can logically group (*) these blocks.
* I.e., if there is a natural heading that could be used (it doesn’t matter if you actually use it) to group several sidebar blocks, use one aside
with section
childs for these.