Any ideas for how to prevent an expense report from being paid if an unapplied cash advance exists?

We are wanting to use Cash Advances as part of our Peoplesoft 9.2 Expenses application.  My concern is that an employee may request and be paid a cash advance, then submit an expense report but fail to apply the cash advance to it and get paid again when the expense report is paid.    We are considering alerts, but would prefer a way that allows the system to detect and prevent rather than rely on an approver to rely on a query or email alert.   Are any of you using Cash Advances and how do you prevent this from happening?  Thank you!