I've been a lurker some time now on this board.
I'd dress her just like I would for Mary, but not in blue. Cover her head with a cloth, secured on either side with bobbie pins. If you don't have time to shop or don't want to spend $$ on fabric, look at your dish towels and see if you have something that will work.
I just thought of something -- the Old Testament Elizabeth, or St. Elizabeth of Hungary? Liz of Hungary's symbols are bread, a pitcher, and flowers. She was a queen, so you could go in that direction, with a crown and cape --plus bread to show she shared with the poor.
Or Elizabeth Ann Seton? You could dress her in black and have her carry an American flag.
Thank you so much for your reply.
How wonderful that this board inspired you to enroll your children in a Catholic school.