Name changed to protect privacy of others. Long 
MIL and her brother are joint deputies appointed by Court of Protection to look after the financial interests of their mother (who suffers from dementia), and is living in a residential home.
The mother's home is still on the market (thankfully), but the furniture, cash from the house etc has been acquired by the Uncle. MIL recently asked Uncle Knob to get his son to make a nominal payment to the estate(?) for a piece of furniture Uncle Knob took from the house and gave to him. Uncle Knob refused. I'd imagine that the savings and current account of the mother would also show some funds unaccounted for. There is a will which specifies who should get these things on the mother's death, but I'm assuming it becomes void under these circumstances?
Uncle Knob has also tried to stop the hairdresser from visiting his mother in the home because 'it's too expensive'. It's a pittance, really improves her quality of life and she has more than enough money to pay for it.
What to do? At the moment the council is paying for her care, but once the house is sold I know they could well seek payment. A man who will steal furniture isn't going to be shy about £££££.
Uncle Knob has refused to speak to FIL, has stated he no longer wants to talk to MIL, and has shown no signs of stopping his abuse. He is actually accusing MIL of having stolen money that went on fixing the mother's home before she went into the house, because he has lost the paperwork. He feels it's basically none of MIL's business to question him or his decisions, but they were appointed joint deputies.
MIL feels conflicted. She's worried about her liability, worried about her mother's care, worried about what will happen when the house sells etc. She's very aware that the last thing her mother would want is her children at war.
Please help. It has been suggested that an easy way out might be to tell the court that Uncle Knob is refusing to talk to her about her mother's affairs, but I'm worried that this could lead to her being removed as a Deputy, which would allow Uncle Knob to stop his mother getting her hair done etc. I'm very aware that the sale of the house or (terrible) the mother's death would complicate the situation immensely and lead to a horrible showdown.
Thanks for reading. Please help! Does anyone have experience of dealing with this or advice from a legal point of view?