What about simply telling your mum it's all sorted, and getting her out of the house - then phoning SS and telling them your father is 'home alone' with dementia, and will be for the next fortnight.

Let them sort it out.

No one has a legal duty of care, not even a wife, so your mum is totally entitled to walk out on her husband.

It is INTENSELY frustrating when those with dementia behave so 'selfishly' (though I appreciate it can't be called 'selfish' as they are not aware of themselves being selfish!).

The problem is that 'waiting for them to agree' ceases to be an option.

In the end, it is why so many end up in care homes. Families just seethe with frustration and anger. I know I did (sigh.)