Hi DeedIDo I'm sorry to hear this. My finding is that this is the first time many of us get to encounter 'the State' - handing parents over to them - and it's a rude awakening.
It seems as if control is everything. If somebody wants a quick exit and DNR, the State seems keen to deny it. If another wants to live and have a chance - as my mother with Parkinson's certainly did - the State will be hell bent on killing them off, by stealth it seemed to me, via deliberate dehydration in the care home.
I know of someone who had your experience, in this case they had DNR but the notes weren't with her when she went into a care home for respite for a fortnight. So they were forced to resuscitate and it was a bad trauma - from what I understand, the hospital basically had to finish her off with a load of drugs, but that is off the record so to speak. The hospital chaplain stepped into ensure it happened, as a mercy.
On the other hand you have my Mum, who had advanced Parkinson's like the OP. Nearly died via care home neglect on several occasions, nobody gets into any trouble ever, put the incidents in the local press and national press, again no heads roll. Came to realise she was on so-called 'end of life' care aka ending life care, via dehydration. Very sinister, care homes had back up via Social Services who seem to be the Gestapo. Saw my local MP Chris Grayling three times over the course of the year, he was all charm but later I suspected he was carrying out surveillance on behalf of Surrey County Council - he's not denied it. Yet Mum was okay mostly, on fork mashable, we could take her out to the pub etc That's why it took a while to catch on that any neglect was deliberate, a variation on the now illegal Liverpool Care Pathway.
Tonight's repeat of Yes Prime Minister made the point - smoking takes 100K lives a year, but think of the money they save in pensions and adult social care. Well, we don't smoke any more so we live longer - the old aren't economically viable unless they get put in a care home for the usual two years, money going to some businessmen who bung it in an off shore shell account and fund the Conservative party.
Eventually Mum died in Oct 2017. For the previous few years my sister and I had to visit her daily to see she was alright, mainly to give her drink. After that, you never trust the State again - not the police, not your local MP, not the Council, not the press who can't run the whole story you find, not the regulators who are actually acting on behalf of the people they're meant to be regulating.