Many thanks, everybody. I very much appreciate your input and advice and experience.
She was (finally) on a drip yesterday on the non-Covid ward when they finally accepted that she was dehydrated, but we were told this morning that she's not on a drip in the Covid ward. I'm sure that's just right hands not knowing what left hands are doing rather than part of a plan.
I don't know about the supplementary oxygen but that's a reallyl good point, thanks - my sister is doing the calls today and I've told her to ask.
Re: capacity, I don't think she does have capacity at the moment because she's deteriorated so much with dehydration over the two weeks she's spent away from home. Even the hospital more-or-less acknowledged that y/day (hence the drip). We have joint LPA for Health & Welfare, though, so as long as they understand and acknowledge that my sister and I should be able to make the decisions she would otherwise be able to make.
Re: coming home, and the risk of her condition deteriorating, I entirely understand what you're all saying. This is of course why it's so difficut. Could be we could get her home and miraculously she'd just remain asymptomatic, or could be she'd go down the tubes very fast. I know she could be dead in days whether she stays there or not, though obvs I hope not. Her care needs were not complex before she went in, except that she'd developed an intermittent balance problem which led to the most recent fall. My sister has been living with her and taking care of her throughout lockdown, and I've been there too as much as possible.
My sister contacted Careline this morning and they've involved a hospital Social Worker, who has been on the phone and has been helpful. She's talking about arranging a Best Interests meeting. Clearly that's a good idea, but we don't know whether our aunt will last until it takes place if it doesn't take place urgently.
Again, I really appreciate your help, and it's good to know that discharge home with Covid is actually a possibility, circumstances allowing. We didn't know whether it was possible or not.