It doesn't have to be a joint account for a person to take money out-- They can have signing rights (signature shows up under the blue light) I have 2 accounts like that, just in my name but wife has signing rights. (I have not had to used them for Visa renewal)
Also you can think about an ATM card with that account and a high withdrawal limit. (100,000 a day) so she could empty account it in a week.
As requested by you in the letter you left.