Can a proxy approve expenses/vacations for a manager?

I have not been able to search out an answer to my question, but hopefully someone here has run across this situation before.

We are running ESS on 5.0.

We have a VP who does not want to have to approve every trip expense and vacation request that route to hm. He wants his secratery to be able to approve trip expenses and vacation requests when he is not in the office or is too busy.

Is this a possibility with out providing the Secratery the same exact SAP Security roles as the VP?

The Secratery currently has a Proxy security role assigned to her so she can enter in time and travel expense data for the VP.

Thanks.

Scott.