Yes. Specify the same flight number for everyone: hers or yours whichever is earlier.
Alternatively go down to the front desk (or at the DME welcoming area if you think of doing it that soon) to make or modify your Magical Express reservation back to the airport. A request for an earlier DME bus than the normal 3 hours before your flight, made in timely fashion, is always granted. Normal deadline is morning of the day before the day you will sadly depart.