OK, thanks to all of your suggestions, I am making much progress. Thank you xpix and tkfm.
I have made Document A just a container with no logic.
I have made another document elsewhere in the tree (arbitrary placement) which will be the compiled slideshow. It will draw from the topical sections by document ID. I upgraded to Ditto 2.1 because it claims to be able to sort by multiple items using &sortBy. I haven’t found any usable documentation on this feature.
The Ditto call now is:
[!Ditto? &parents=`[*tvlist*]` &sortBy=`menuindex` &sortDir=`ASC` &depth=`1` &tpl=`slide` &display=`all` &debug=`1` !]
This collects all of the slides I want by the parent IDs I place in my new TV, but unfortunately it interdigitizes them (section1slide1, section2slide1, section3slide1, section1slide2...) since each section has an ordinal in menuindex that specifies its position. I would really like to sort by [parent, menuindex] but when I set &sortBy=`parent, menuindex` or &sortBy=`parent menuindex`, I get no desirable result.