Who has final say in this situation?

Has there been a multi agency meeting or have you just had a conversation with the SW and GP separately? It sounds like the SW has suggested continuing care funding, which is extremely difficult to get. They can carry out the initial checklist to determine if as assessment should be carried out but they do not determine if someone will qualify for it.
My suggestion is that your DH and BIL withdraw all the support they are currently providing so that both your MIL and SS can see just how incapacitated she is. Get a fall alarm for her, which she can use but let the service know you are not available between certain hours so they would need to phone an ambulance or police if she was to contact them. She may well be taken to hospital and from that point it is more likely that she will be moved into a nursing home, which by the sounds of it is what she absolutely needs.
What is happening here is that you’re all masking her true needs by doing everything for her, understandably so.

Even though her sons have financial POA as she still has capacity, then any financial decision has to be enacted with MIL's permission....they can't just be paying for PA'S, washing machines etc without her say so (until such time as she loses capacity)

Even without dementia elderly relatives can just say what they think will get the medics / SW off their back. Pretty much every appointment that SIL wasn’t able to sit in on, FIL would say he was absolutely fine, eating and drinking well, still able to drive, yes my DD is round every day, taking all medication as required. When in reality he was barely eating or drinking, confusing all his meds, smoking in bed (and falling asleep, had had multiple accidents in the car so SIL took his keys away.

it’s really important to be in the room during these meetings. You can outsource a lot of the care but this is when you really have to be present and to be heard.

A live in carer? Gosh! What world is this? Here SS will offer 4 visits a day. That’s it. They prefer this to suggesting a home if they think they will pay. It does take ages to persuade anyone to leave their home and the elderly get very attached to them. Then dementia kicks in and they are not able to make sensible decisions. Only ones they would have made 10 years earlier. SS do not want to spend any money. DM was never visited by a social worker or anyone to assess her ability to be at home. If you care, they let you do it.

I've never heard of a registered carer. GPs do not give a fig about that either. Anyone can contact charities and be “signposted” to help. Then the help says it cannot help. Even getting paid help for DM took 20 calls to companies and those professing to help. They don’t. So the only answer is a home. Your DH must start to get tougher.

This is a much more common scenario than people realise. Very often the elderly person just refuses the care home option and wants it to be their child(ren) doing that care. Social services tend to go along with that as they are all told to save as much money as possible, and family doing it is cheaper. For that reason they will accept the person's word even if, looking more closely, the story about how they are looked after doesn't stand up. My dad said 'my daughter does that' to everything and that was that. So unfortunately, as pp have said, the only way to prompt change is for the sons to stop doing their current load. Sadly things have to go off the rails before you can get them to change.

The better level of care is probably because if your husband and his brother have been paying for the carers, that's bypassed the system. It should really come from the assets of your MIL and at this point they don't count the house, it's what she has in the bank and as income. If she has roughly under 23K they'll pay some, if under about 16K they'll pay all. It would be worth a fuller conversation with their finance people about this. You might be as well to agree trying their suggested higher level of care - that way, you've agreed to it and can later say 'look, we tried this but it just didn't work' in support of her actually needing residential care.

Good luck - it's upsetting to have to be the bad guy, but often it's the only option left.

@abovetheweather , after having spent many years caring for my own parents both in their home and after my mum died caring for my dad in my home I do understand your predicament.
My first thought is that you should all be registered with your GPs as carers, when I registered as a carer various agencies contacted me and had useful advice on potential help available. Speak to age concern they may be able to point you in the direction of charities etc who could offer support. Have a word with local churches (your MIL does not need to be religious) and ask if they have a befriending service. Basically get all the free help you can going in to her. If MIL has funds employ a home help a couple of times a week for cleaning, doing her laundry etc. Could she afford extra carers? If and when you think her condition is life limiting see if her GP will refer her to a hospice they were so helpful to me and managed to get my dad a live in carer (in my house).
She doesn’t want to go into a home and appears of sound mind so you can’t force her but you can arrange POA for any future need. It is really hard on the children of old people in these circumstances your husband is lucky that he has a brother to share the burden, I have a brother but he abdicated all responsibility.
PS
Suggest the brothers subtly clear her house of any rubbish because that will make one task that lies ahead easier when the time comes.
Well done to you all.

The trouble with dementia is that they truly believe that they are doing all those things! We found our social service visit no help at all. I wanted them to look behind the sofa where there were hundreds of old teabags wrapped up in newspaper and see the fridge and freezer full of out of date food, but the SS lady “didn’t want to stress M any more than she already had” and left. We found talking to a care home was much more productive- they came to see her and managed to talk her into a trial fortnight at their home while we “were on holiday and the carers couldn’t come”. They managed to arrange deprivation of Liberty after a couple of months.

I had an issue with DM when she listed all the food she cooked to an OT. It was pure fiction. Luckily I spoke to the OT. People sound plausible so they are believed. However in this case it’s not plausible she’s doing anything for herself. I really would talk urgently to SS and get her safely in a home. Care at home is minimal and she’s clearly not capable of living alone.

One extra thing - if / when your MIL is interview re Deprivation / section make sure your DH / DBIL is literally in the room. As others have mentioned some very interesting tales get told about how they are managing quite well at home thank you.

Yes, I realise that, @AnSolas, but the actual taking of medication is presumably working day to day (for now).

Thats a big one
As most LA carers will not "give" meds only "prompt" meds. One instance the carer decided that included not popping the pills from the scheduling packaging and getting a glass of water.
The pills were kept out of the reach of the person due to not being able to physically extract multiple items from section of a 4/7 weekly tray.

Tell me about it! Just before Christmas my mum told the SW that she manages her finances using her computer. She has never done Internet banking and her tablet hasn't been used for at least 6 months as se thinks it's broken, DB looks after her bills. It only needs charging but I don't charge it for her after she used it to find someone to do a small job in the garden and they charged her £000s. She also told them she does 2 activities every week. One stopped running over a year before and the other she hasn't done for nearly 20 years. Also does all her housework when she has a cleaner that does everything including laundry (sourced when the house got really grim abd no clean clothes). All taken on face value while I was struggling to deal with actual unsafe behaviour that had triggered the assessment

Capacity assessment is supposed to check that you understood and weighed up the information and came to a decision.

All too often it's a superficial 'they said they want this'. With no corroboration from those around them to check they weren't talking complete bollocks.

Ah the capacity trap - which basically translates as long as you can express an opinion on your care or treatment, irrespective if it's inconvenient, silly or unsafe, your opinion is the one that's followed.
Precisely this.
All you can do is withdraw care and hope it wakes up both the elderly person at the centre of it all, social services and the GP.

If she can make her own decisions that’s it. End of. The law is there to protect people to be able to make decisions even if unwise. If it’s gruelling, stop. Stop. Tell SS you’re not doing it anymore they will have to add support. Or you can pay privately. She isn’t at risk if she can’t get out of bed. She has carers doing the day to day care. She obviously would rather live this way in her own home then go to a care home. Unless she has something that means she doesn’t understand the implication of her decision then she should be able to live as she wants

The final choice of what your MIL does is up to her (as long as she has capacity). The final choice of what your DH and BIL do is up to them.

The only control you (or rather your DH and his brother) have is to choose to stop propping up an unsustainable system. No one is going to have that conversation with your MIL for them and no one is going to take them seriously until they actually stop.

What do the brothers think about this? Are they willing to step back from active caring?

If so they probably need to have another go at explaining this to MIL. No soft-soaping it, they need to explain to her what a detrimental affect it’s having on their lives and their families lives. But only as a prelude to telling her that they are stepping back and what will happen instead: if they want her to absolve them and tell then it’s fine to stop doing this they will be waiting a long time.

At the same time they need to alert Social Services, and prewarn them to get more care in place. TBH I’m surprised they have offered help with laundry, housework, shopping - I’ve not heard of that happening.

You are absolutely correct that the bigger picture is not being considered- the house, her health (other than what the carers observe), etc. and this is not the responsibility of SS. This is the reality of an older person, living alone and becoming less able to deal with all these things. Presumably the sons will still visit. If they have financial POA, can’t they go ahead and organise the purchase of a new washing machine etc?

I would stop referring to MIL as having 'short term memory loss' and start saying 'undiagnosed dementia' - it stops people minimizing the situation. Undiagnosed as she is now too unwell to go to memory clinic but clearly has dementia.

Her history sounds very typical of the decline of dementia - had a fall, dementia had affected her motivation so she didn't do any physio, now bed bound, dementia got worse - doubly incontinent, house falling apart as she can't make any decisions.

Sadly she probably isn't grieving and doesn't mention her late husband very much as she doesn't remember that much.

The GP is more than likely correct, she would be better off in a care home. Obviously MIL doesn't want to go as she has no insight into any of the current problems.

As the brothers have POA for finance, I suggest they start using it to support her care and stop doing things themselves - pay a cleaner to clear the fridge and empty the bins and do the laundry, cancel the newspapers, get prescriptions from an online pharmacy that delivers.

Basically they need to stop seeing themselves as the solution and outsource so they are not visiting and exhausting themselves.

Then if Social Services think she can manage with more care, they put that in (minus the brothers) and the results will be obvious very quickly.

Her two sons (one being my DP) visit every other weekend to shop, clear out the fridge, empty bins, keep on top of her prescriptions, sort out her newspapers etc. They both live 2.5 hours drive from her. It's gruelling, and affecting all our family lives, and we need more help.

As a stop gap, and as they have financial POA, they could employ a PA to do most of that. Presumably the only tricky one would be the prescriptions. How much involvement do they have there? Presumably she has dosset boxes?

Deprivation of liberty can be used where the elderly are a danger to themselves. She cannot do anything so is clearly a danger to herself. She’s not thinking rationally. Definitely speak to GP. The sons need to withdraw support and let SS and GP know this is happening. Just deal with money and be firm about caring. This situation obviously cannot continue.

You are paying the carers directly.
Get them to record how her memory and decision making capacity is failing during daily visits.

So even if she passes the capacity test at the moment that her decline is tracked as some people do perk up for the SS visit and look more capable than they otherwise are.

I doubt she would be sectioned as she's not a danger to herself or anyone else.
I agree , withdraw family support , it's too damaging for her relatives and their families.

Reduce / stop all support from family, citing carer breakdown and wait for it to reach crisis point and push for a hospital admission. On discharge insist that MIL can no longer remain safe in her own home and needs to be discharged to a care home as the family no longer provide support. It is unbelievably difficult to do this (we are going through this at the moment) but it is the only way to push it if Social Services and the GP won't step up to intervene. And for as long as you provide support they will think your MIL is coping.

All the sheltered accommodation I've looked at would refuse to take her due to her level of need. Someone who is already there and deteriorated is different.

If you MIL has capacity then she has final say. Obviously. Even if welfare POA is set up

Bur obviously your DH and his DBro have final say in what care they will provide.

Can you try it more on the basis of respite care first e.g. the carers will be away so going to do respite care for a few weeks. She may love it enough that she wants to stay.