Dad (88) recently gave the oldest of 3 brothers POA. The rest of us just found out about it and are concerned with his choice. Our brother spends money like water, has filed bankruptcy in the past, has greedy children, and makes jokes about selling the house to himself for $1 (not around Dad). Our mother recently passed after a long illness and his biggest worry seemed to be that mom "dragging" this out means more hospital bills. Finally I just found out he has been sharing Dad's financial details with other people. Dad saved his money and lived frugally all his life. Dad is of sound mind and seems unconcerned when we brought this up to him. I'm thinking about bringing up to his financial advisor (who is also my advisor) but worry it will cause a rift. I don't care if Dad gives all his $ to charity I just want to make sure it goes where he decides.
Why do you suppose Dad has made the choice he did? Dad must know of POA Son's financial history. Why wouldn't he select someone more responsible? Do you suppose he mistakenly thinks it has to be the oldest son?
I think that mentioning the issue to his financial advisor would be appropriate. This professional could perhaps help your father think through what the issues are and what to consider as he makes this assignment, without getting into siding with one child or another.
If your oldest brother behaves in ways the rest of you consider irresponsible, there is going to be a rift. I don't think you can eliminate that possibility and while maintaining family harmony should be one of your top priorities you still need to do what you consider the right thing.
Do what you can to make sure Dad is taking this decision seriously, and then accept his decision.