@ByCalmBrickPanda What a lovely thought. My daughter is profoundly disabled and has carers through direct payments, she's only young so she has care at home with me. I am also the registered manager of a care agency, I worked my way up from being a care worker at 19, so live in this world all the time!
I think a cash gift is lovely, even with the best agencies care staff are horrendously underpaid for the work they do. As others have said your daughter's care staff likely have it in their code of conduct or similar that they are not allowed to accept gifts, my staff cannot accept any cash and can only accept small gifts up to a value of £10.
When my daughter left nursery a couple of years ago I wanted to get her 2 amazing workers (they accompianed her to nursery because of her complex health needs) some money, I knew both had very little money and they both had young children themselves and I felt that money would be much more meaningful for them. They work for the NHS so absolutely can't accept gifts. I'm not necessarily recommending this but I casually asked both of them where they lived, tracked down their individual houses and anonymously posted £250 through each of their doors with a little note. They both must have known it was me but no-one said anything.
You could speak to the manager about how you can go about this, although to be honest in my organisation I don't think I'd accept, intead I'd ask for a donation as we're a charity, which it not really what you're seeking to do. Although you could do a big purchase for the household with that money, e.g. a hot tub which while mainly for the tenants rather than the staff, if it improves people's quality of live it also makes staff's jobs a lot more enjoyable and often run smoother.
If it was me I would be cautious about saying you'd come into money, just in terms of making yourself vulnerable. The other things I'd just take some time to think through:
-Is there any staff you may miss out? Does this have the risk of causing friction?
-Are you okay with the possibility of one of the staff members leaving soon, or even worse if an incident happens with them and your daughter is harmed? Not saying it will happen but I've learnt to expect all sorts of shenanigans with even my best staff.
-There may be a possibility that this becomes expected of you, or of other staff wanting to transfer to your daughter's house.
-If there is ever issues over money in the future then there may be an expectation that you can foot the bill for extra needed things are you have money.
Upon reading what I've written I feel it sounds a bit negative which I didn't mean it to be. They're just things to consider.
I am so happy that it's such a wonderful placement with great staff, it gives me hope for my DD's future.