Legal Question in Wills and Trusts in Illinois

To whom the bank accounts should be distributed is governed by the account agreement with the bank where the funds are held, not by what the will says.

Your father's will can only pass property that goes into his estate. His joint bank accounts with your stepmother are governed by the account agreement. Most joint accounts carry rights of survivorship, which means that all rights to the account end up with the survivor. If that is the case, the funds in the account belong to your stepmother to do with as she chooses. She has no obligation to dip into her own money to fund a bequest under your father's will.