Phyllis,
Your sis will have to claim the baggage before going through the customs. You won't have access to that area. Try to find out where exactly the plane arrives and meet her after the customs.
If you know what terminal, you can always fix a different spot like a particular shop as a back up. It seems there is an American Express counter, a Brioche Dorée, a MacDo, etc. after the customs (public zone) at CDG1.
http://www.adp.fr/webadp/a_cont01.nsf/NFhome@ReadForm.htmlClick 'horaire des vols' and the arrival locations will be listed.
Seems like Terminal 1. But do double check again.
There is most likely also a so-called 'meeting point'.
Maybe, someone else has a concrete idea as a back up. I am not that familiar with CDG, since I usually fly in/out Orly, when taking the plane from Basel.
Bonne chance and have a great time with your sis.