First I think there are the facts.
You might be related but that does not mean you need to love them or even like them.
You might be related but you have no legal obligation to care for them or even arrange care for them.
She no longer has any power over you for the reasons stated above.
You, out of the generosity of your own heart have CHOSEN to stick around and do what you can do to help.
The extent of this help is on your terms. You can choose to walk away at any time and the law backs you up on this.
So, what have you chosen to do? That's the next but.
Get a pencil and paper and make two columns. One, the things you are prepared to do and two, what you are not prepared to do. Compare notes with other family members and stick with the boundaries you have set.
Take the column that lists what you are not prepared to do. Remember you have the absolute right not to do these things. I think as a minimum though that you should make the powers that be eg Social Services or her GP so that they can make arrangements to cover those areas that you and the rest of the family cannot. Then step back and let the system kick in.
None of this has to be done in a dispassionate way. It is right that your limits are acknowledged.
Turning to the behaviour issues. What you are experiencing is normal dementia behaviour. The behaviour is borne out of confusion and fear and is accepted generally that if someone is so far down the road that they are looking to come live with you etc, then the dementia has probably developed beyond the point where the person could be consistently manipulative in the way her behaviour is being interpreted. In fact what you are probably dealing with is a scared old lady who has forgotten the ills of the past and is in fact desperate for someone to help her find a way to cope with all the fears and challenges that dementia can bring. It could be that she is approaching the stage where she is not able or is uncomfortable living on her own.
That having been said, NO-ONE is required to put up with abuse or violence. If she has displayed this behaviour then you must all have a plan in how to deal with it. First thing is, make sure you have your mobile phone on you at all times. Next do not engage with them and leave the room immediately you see signs of agitation. If in the house then move to a room with a lock on the door then call out for help. Leave the house and sit in the car then call for help. People can look frail but can have super human strength when agitated so do not take any risks wait your help. Do not rule out calling the police. They have direct access to GPs and SWs and hospitals etc and can be very understanding in the circumstances. Sometimes their involvement means you can jump the queue to get mum the help she needs. If not the police then there is a duty social worker on hand 24/7. Look up the phone nr and stick it in your phone.
Finally there is Talking Point. We'll support you and share experiences with you so you're not walking this path on your own. We don't mine people ranting on here if it helps you deal with things.
Edited to add this thread that gives some good tips on communicating with some one with dementia. Might be helpful if you share it with your siblings too.
http://forum.alzheimers.org.uk/show...ionate-Communication-with-the-Memory-Impaired
Take Care,
Fiona