by Ken Golliher: Account ownership and survivorship provisions are determined by state law. Check yours to see if they provide for contingent beneficiaries. (I sincerely doubt it.)
Contingent beneficiaries are common on IRAs. There, your beneficiary designation form (probably provided by a vendor) provides the necessary language.
by John Burnett: The only state that I know of whose statutes provide for contingent beneficiaries on a deposit account with a POD designation is Oklahoma. That doesn't mean that there aren't other states with such a provision; it does mean that you need to understand what your state law says on the question, as Ken has suggested.