Background: my father is 92 and (thankfully) no longer drives but has a disabled parking ticket from the last couple of years of driving. He is up and down with physical health and finds walking difficult. My DM is 86 but pretty fit and active and does everything, going into town every day etc. If he is OK to walk a short distance, he will go with her but otherwise, he stays at home.
My DM is very reluctant to leave him, partly because the last time I took her for a day out to London, he had a terrible accident which could have been much worse. If he's not feeling too good, she will make a mad dash around the shops and get back to him - on these occasions she will not use a disabled space. Yesterday she and I went into town (she drove) for specific things for him, which she ended up not getting because it was a Saturday and there were no spaces other than disabled ones. She would not park in these because the disabled ticket has his name on it, so he ended up doing without as she was too concerned to leave him for too long.
I know that parking spaces are often discussed on here and I am prepared to be told that IABU for telling her that on this occasion it was OK (she didn't anyway, but this will happen again) - and I genuinely don't know the protocol.