Eventually, I went to an Apple Store and showed the whole phenomenon to a Genius Bar guy. “That’s odd”, he said. There was much consulting with colleagues and research on the internet, and on their own Apple database. To cut a long story short, it seems the problem will need software fixes to IOS 13 and to Watch OS6, which will be developed and rolled out ... at some point! They thought it would take a while, somewhere in the order of 6 weeks to 2 months. Not the best news, I’m afraid, but at least I’m now fairly sure that the hearing aids/watch/phone combo will, eventually, do what I wanted. If there is any change, or there are any further developments, I will try to remember to post here, so that you from the future, trying to solve a similar problem by searching the internet, will know how it all ended!