We are a professional association--think AIGA or the AMA--the staff (including Graphics department) are employed by the association and other staff only use Office products. Only the graphic designers use Adobe apps. The volunteers are SMEs who are scientists, engineers, researchers, etc. who volunteer their time to write the technical standards which various industries (and government orgs) use in regulations or SOPs. They are members of the association, but not employees of the association--they actually work for other companies like engineering firms, oil companies, paint manufacturers, contractors, etc. The only common denominator is Word.
Their knowledge of Word is often very limited and rely on templates we provide them to write these standards. For new standards, it's not an issue, they have a template with dummy text and all styles appropriately applied. It's the standards that have been around for awhile and that are coming up for review/revision. We use our InDesign template and flow in the Word documents that have the correct styles already applied. Then we have some cleanup and we add images. We do editing with staff through Adobe's Share for Review (the volunteers aren't involved at this point) and once approved, we export a PDF that has all the graphics, styles, and branding. Security is applied to the PDF and the PDF is uploaded to our online store. The general public only ever sees the PDFs. We export a Word document from the PDF which retains the flow and look, but none of styles transfer. If anything gets deleted and replaced, they don't have the appropriate styles to apply, then the designers have to apply all the styles. We want to give them a document as close to the published document as possible but with the styles applied.
All standards must be reviewed at least every 5 years (sometimes sooner if regulations change). At that point, the volunteers take the previous document, make updates and resubmit to staff. Then the designers make a NEW InDesign document (by our bylaws and legal purposes, we have to keep all versions, so a new one is created when there's a change), and flows in the text. It won't be the same volunteers--they rotate out of their committees every 2-4 years--so it's new people. It might even be new designers.
Until our integrated CMS gets implemented, they have to use Word because it's the lowest common denominator and they already have it. The plan is, once the CMS is implemented, the standards will start and end there. But until then, we have to do the other way.
Again — I not only have general experience in this area but specfic experience with the sort of work organization you've outlined, so I understand the dynamics of the material, the authors, the budgeting and the general 'personalities' involved. The need for a relatively unskilled source — authors, SMEs, organization managers, etc. — to be able to write, submit, review and update material, while a more professional publication crew makes them look, well, professional is... common.
The only real solution I know of is what I suggested: that the "final" file document be in Word, with what's produced in InDesign being passive publication. This won't change no matter what authoring, info management or CMS tool you might use; once the material goes into ID, it's as out of reach for the authors as book printing plates.
Construct a workflow where the content is live, then archived using a versioning system (which RARELY requires document control and versioning applications — the insistence of software teams to insist otherwise has driven me batty over the years — and ONLY when there is a final, publication version is it pulled into InDesign, in a one-way, one-time step.
In about forty years of doing much this general work and workflow, I've never found any software, converters, filing system, versioning system or magic wand that lets publications be seamless from a blank Word file to anything like a printed professional layout. The tools change, and get more sophisticated, and we get nine kinds of file sharing and storage a year, but that fundamental divide between "mass authoring" and "professional publication" remains. As Bob L. says, it's a Holy Grail and unless you've got Indiana Jones on your team, you aren't likely to find it. 🙂