I agree the Estate Planning board is a good source of Foolish advice. Also, while your DS could write checks on DF's account, you could actually open new accounts in his name with Power of Attorney. It sounds as if DF is trying to distribute the responsibilities so no sibling feels like they are being left out. What you and your brother and sister need to do, however, is get together and make your own plans together so that what often happens in other families doesn't happen in yours, that one sibling objects to what the other is doing with their respective "power" and the infighting begins.

Fuskie
Who is not a lawyer and only has vague ideas as to what his own DF has planned but knows his lawyer does...