Is the son obligated to inform the other heirs about his father's financial expenditures during his lifetime, knowing that he held a legal power of attorney from him, and that the father managed his own money and paid off debts himself?

The agent is trustworthy and does not guarantee what he has been entrusted with unless there is transgression or negligence. If the agent claims to have returned all or part of the money to his principal, his word is accepted under oath, because rejecting his claim would deter people from accepting trusts. This ruling applies whether the agent makes this claim during the principal's lifetime or after his death. Accordingly, the siblings have no right to demand anything from their brother that he claims to have given to their father or spent on what he was entrusted with, even if he has no evidence.