Everyone needs to start the conversation with their loved ones as soon as they can to question anything that seems out of character. It doesn't matter if they sound like or look like them - if anyone is asking for money or sensitive information, question it no matter what.
I know a lot of folks may feel like that's an impossible task, especially with parents and older relatives, but it's possible - I just recently had a conversation with my parents, and I was bracing myself for it to be an uphill battle, but they were switched on and got it. You've gotta at least try.