Dad has dementia, 2nd wife incompetent POA.

My 89 yr old dad has dementia. His POA in order is his wife (89 hrs old) then Dad’s kids in descending order. They’ve been married 11years. His wife was just scammed, twice in one week, out of $60k (she gave it to them out of a joint account). She keeps telling my dad that he did it but it’s been proven, by his financial advisor, that she did it (he doesn’t have computer access or a password anyway). She is incapable of transferring funds from one account to another, and figuring out basic banking. She has to get her daughter to help with taxes, banking, etc. We have told her that her daughter is not my dads POA and dads next in line needs to take over as POA. She says this is “her” business. She does not pay for anything, it’s all dads money; she has her social security put into her own personal account. There’s what she calls “her” money and then “their” money. We are still trying to unravel/straighten out the mess she made from being scammed multiple times. She continues to get on her computer without virus software which is how she got scammed. I feel this is a sticky situation. Not sure what to do or how to convince her that her daughter is not to be involved in the financial business. Dad does whatever she says.