The best thing a Rho Chi can do is look honestly at herself and really, truly make sure she is disaffiliated. If you "strongly encourage" a girl to go back to your house when she doesn't want to, she'll remember it later.
Our school used recent alums for Rho Chis, and that worked much better, I believe. Some even went to other schools and so were in chapters we didn't have. I think this allowed them a little more distance and objectivity. Plus, you had fewer pictures to cover their faces in!