I would say firmly that said aged parent can fully afford to buy the relevant equipment for themselves, but chooses not to, so presumably does not want it.
Can the sibling so insistent that your Aged Parent needs the equipment guarantee that, if said parent has it, they will actually use it? You could all be wasting your money on a white elephant.
I have my own experience of buying someone equipment I was convinced someone needed, but they refused to buy for themselves, only for them to leave it in the corner of the room and never use it. They didn't buy it because they had decided they wouldn't use it -and they didn't.
Why not suggest to your sibling that you rent the equipment first from your local Red Cross or similar organisation. Then if your Aged Parent takes to it you can suggest to your parent that they buy one for themselves. if they do not use it the equipment can be returned to the Red Cross.
If your Aged Parent wants to suffer because they are too parsimonious to buy equipment that would help them, then that is their priviledge. I can see no reason why anyone should buy the equipment for them.
I would never contribute to buy something for somebody else on the insistence of a third party that they really want it
I would tell your sibling firmly that you are not prepared to contribute towards something your Aged arent can well afford to purchase for themselves, that the organising sibling cannot guarantee the Aged Parent will use, even if they have it.
Taking dogs on holiday in summer
