Hi Alora
The key to all of this is being sure to act in Mum’s best interest which seems to be exactly what you are trying to do. I would, however, question your brother’s motives if he has already said he will not spend money on care. Unfortunately with dementia and your mother’s age, things are sadly only going to get worse.
I have had similar with my brother although I am the sole holder of the LPAs, I manage her finances and my Mother lives with me. Our row was about me spending money on respite care whilst I had the audacity to go on holiday. He tried to take my Mother to a solicitor to get the LP A overturned. I found the Office of Public Guardian really helpful. They said it would have to be my Mother who appoints a solicitor to get this actioned and the Solicitor would have to be reassured that my Mother could demonstrate competence and capacity to give such an instruction. A solicitor would or should require a formal Assessment by an expert - these are usually qualified independent consultants. My point about this illustration is that your brother cannot just get the LPA taken away from you. He must follow a fairly complex process lead by your Mother without his prompting Or coercion. His only other route would be to take you to court as an unsuitable to act as a power of attorney. This is an even more complex process. I would therefore suggest that you speak to the OPG (again) about your brother and get her file flagged so that they may be aware of the possibility of a vexacious attempt to remove you as LPA.
You need to stand your ground and not fear his threats. As joint holder of the LPAs you have a joint legal responsibility to act in her best interests. I therefore do not think it unreasonable for you to ask to see her bank statements. Indeed, I would go so far as to suggest that this is about acting responsibly. Furthermore, he needs to understand that a plan of support to meet present and future needs is probably overdue for a 96 year old lady with dementia.
I also think that a review with her Dr would be in order which if I were you, I would call him/her and raise your concerns and have the Dr initiate a health review with your Mother with you in attendance. (It would be helpful to file the Health LPA with the surgery if not already done so.)
I would also get the Dr on side to help initiate a care review with Social Services. To get this done can take a long time and a lot of badgering as their priority is safe guarding, but in my experience they will respond eventually - especially if you emphasise that you believe her to be at risk.
I recognise it will be an uphill battle with Mum, but if she can see the benefit of help, she may well become less resistant. I have two private carers that I started using purely for her entertainment - e.g taking her out for coffee and cake. To her, they are friends rather than carers and she now really looks forward to their visits.
I hope you are able to resolve this. You clearly love your Mum and want what is best for her. I am so sorry that you are having to fight to get the help and support she so clearly needs.