Dear thesis writers,
after a long time spent experimenting and “debugging” my workflow I think I finally got a fairly satisfactory solution which I would like to share with you, fellow sufferers 
The end goal is to be able to write in Scrivener, compile, send to my supervisor, who makes changes and comments, efficiently integrate those in my original scrivenings so that I can reiterate the process again if needed and I don’t have to move and stick to Word after the first draft has been compiled. And doing all this using zotero as a references manager.
So, here is how I do:
First off, I’ve organised my binder as follows: Chapter as folders, Sections as documents, Sub-Sections as sub-documents. I use the <$hn> code in front of each section for automatic numebring. Thus:
1. I write my chapter sections, usign Zotero RTF-scan syntax for inline citeations {author, year, page}
2. I create a collection for the current chapter elements only
3. I sync the collection with an external folder thus creating individual [i]sectionX.rtf[/i] files
4. I then compile all the elements in one file [i]chapter-draft.rft[/i]
5. I run zotero's RTF-scan on it: [i]chapter-draft(scanned).rtf[/i]
5a. I copy and paste only the automatically genereated bibliography to the [i]chapter-draft.rtf[/i] in order to avoid losing the inline citation syntax for further iterations of the revision process: I've instructed my supervisor to trust that the { brackets will be replaced by the ( ones in the camera ready version of the file, yet he still has access to the full references list should he want to check some. (I use a similar trick for table and figures refs: I tweak the code $$n:figure:uniqueimagename> instead of <$n:figure:uniqueimagename> to run a simple Find&Replace $$n to <$n when I'm pretty sure the numbering will not change. Or you can handle this in Word in the camera ready version).
6. I send it to my supervisor
7. I get it back with his tracked changes and comments
8. I approve changes in Word (normally, one click "Accept all")
9. I open in Word every single [i]sectionX.rtf[/i] from external sync folder while having the supervisors’ commented [i]chapter-draft.rtf[/i] (or .doc) open - possibly on a second monitor
10. I manually copy and paste section by section from it to each individual [i]sectionX.rtf[/i] files, overwriting their content
11. I save them all
12. I open my Scrivener Thesis project for syncing: I get notified that documents have been updated and I'm presented with the Updated documents collection automatically, while a snapshot of my original version of the sections is automatically taken, [i]Pre-External File Sync Overwrite[/i].
13. I immediately take snapshots of my supervisor’s version for all the (updated) sections, with title: [i]Spv-Revision_date-sectionX-snapshot[/i]
14. I proceed to in depth revision using vertically split editors by dragging the relevant snapshot on the heading of the second editor.
14a. If I haven't made changes since I sent him the compiled draft, the comparison is between his commented version and my [i]Pre-External File Sync Overwrite[/i].
14b. In case I had to make changes in the meanwhile, I damn myself for not being able to stick to sensible deadlines so that I have to grapple with this versioning mess once again, then I roll up my sleeves, I roll back the [i]Pre-External File Sync Overwrite[/i] and I option-drag the [i]Spv-Revision_date-sectionX-snapshot[/i] for tracking changes comparison, taking in account his comments looking at a print out of them, unless you want to rerun the side-by-side comparison between the Pre-sync version and your Supv's snapshot with comments dragging the latter on the editor without the option key pressed once the track changes revision is done.
Morale: don’t touch your scrivenings while you wait for your supv’s feed-back if you can afford to do so.
Now, for this to work, I assume that structurally sections and subsection stay the same, thus the revision is at the content level only. If it changes, you’ll have to redo the section numbering.
I hope it’s useful and if more experienced users have elaborated a smoother way, please advise. Thanks.