"What I find frustrating about Aitch's posts is that she has repeatedly said that she "doesn't want to be called anything" and that it should be obvious to HCPs that she is her children's parent but not their mother (hope I have got this viewpoint right)."
no, you haven't. not only have you got it wrong repeatedly but i've corrected it a couple of times, as has HerBeatitude, so i have no idea why you are so fixated on it.
it should be obvious to any HCP that i am not THEIR mother. their mum, presumably, took them to school, baked birthday cakes etc, maybe even lives in a house with their dad.
what i've said is that if it's genuinely too much trouble to ask a person who they are and how they wish to be addressed, then they can just call the person 'you' in any case as this will cause no offence.
vide, 'Mum, could you hold her arm/Mum, can you sit there please?' vs 'could you hold her arm/could you sit there, please?'
just calling the person 'you'... no harm, no foul and it wouldn't send anyone's blood pressure sky high i think.