I would template your workflow with InDesign by creating a standardized CSS you can import and default paragraph and character styles. You can then output as a PDF for the approval process and HTML. However, be advised if you start adding tidbits to the character and paragraph styles it will make your CSS convoluted.
Another solution could be generating in XML and use many tools you can research on converting XML to PDF then bring it into InDesign as IDML but this would probably require Adobe’s InDesign SDK and you have to go through an approval process now which, if I recall, it took three weeks before I was approved.
If I may be missing something by your question please let me know and I will go into further detail with my answer.