Apologies but this is quite long - would like external viewpoints so will attempt to present the facts as neutrally as possible:
Two sisters, let's say Ann and Barbara. Both 60+, largely NC due to not seeing eye to eye over anything, but particularly over the care of their elderly mother, henceforth known as GM.
GM has had worsening dementia for some years, but has lived alone with increasing support from carers, and from Ann who lives close by. Ann has always lived close by, has seen her mother regularly, and has both powers of attorney. Barbara emigrated 20 years ago but has remained fairly close to her mum. Barbara is not well off, and a couple of years ago Ann noticed that money was regularly leaving GM's account, going to Barbara. It transpired Barbara had the bank details and was basically helping herself - but claimed she always asked and GM said it was ok, which may well have been true. Whether GM was able to make such decisions is debatable. Large fallout ensued, Ann stopped Barbara's access to the bank accounts as she felt she was taking advantage of GM. They have been NC since.
This summer GM had a bad fall, and it became clear she would not be able to leave hospital to return home, and would have to go into a care home. Ann arranged all this. Barbara was informed and never replied. GM's flat had to be sold, and Ann's son and DP said they would he interested in buying it. Ann had the flat valued by several agents, and has arranged that it be sold to the son and DP for slightly less than market value to reflect the fact it is a private sale without agents fees. The price agreed has been declared reasonable by both parties' solicitors, and has been approved by the office of the public guardian.
GM now needs 24 hour care. She is settled in her home, and while though the loss of familiar surroundings and her fall have undoubtedly worsened her condition, she seems as happy a possible in the circumstances. The sale is going ahead with exchange due just before Christmas and the proceeds will enable her to remain at the private care home for as long as necessary.
Barbara has now emailed Ann to say the sale is illegal as the house was not offered on the open market, that she will be returning to the UK and removing GM from the home, and intends to move herself and her DP into GM's flat to care for her. She intends to take Ann to court if she refuses any of this. Ann is very upset and worried, as are her son and his DP. Not least about the impact on GM if she has her surroundings changed again and is left to inexperienced carers.
Has Ann behaved badly allowing her son to buy the flat?! Can Barbara remove her mother when Ann has power of attorney and placed her there, and GM definitely no longer has capacity?!