If you suspect person has not got capacity, ask for them to be reassessed,biggest mistake I made in not doing so,other option if POA in place is to contact the OPG or if you suspect fraud contact the Police, a word of caution though contacted OPG & Police it has taken years for them to for me do the right thing, sadly too late though, see excerpt below.
CHAPTER 4: SPECIFIC GUIDANCE ON EXERCISING CONTINUING POWERS OF ATTORNEY:
MANAGING THE PERSON'S FINANCES
4.1 You are not obliged to invest the person's estate for maximum profit but you must exercise at least the standard of financial management that he/she would expect.
4.2 You are not obliged to do anything which would otherwise be within your powers if doing it would, in relation to its value or utility, be unduly burdensome or expensive.
4.3 The funds and assets you are managing still belong to the granter and you should usually keep the person's finances separate from your own or anyone else's There may be occasions where the granter and attorneys have agreed in the past to keep their money in a joint bank account. It is possible to continue this. But in most circumstances attorneys must keep finances separate to avoid any possibility of mistakes or confusion.
4.4 If you abuse your position, for example by using the granter's funds for your own benefit, you may be liable to make good his/her losses. It is also possible that anyone investigating your actions may consider such use as theft or fraud and report the matter to the police or, if you are a professional person, to your supervisory body.
4.5 If you live in the same household as the granter, the use of his/her funds for household expenses that benefit you as well as the person will not count as abuse.
4.6 If you act reasonably and in good faith, and in accordance with the principles, you will not be liable for any breach of any duty of care or fiduciary duty.
Hopefully this will help
All the best