I am the White Rose sweetheart for Sigma Tau Gamma at Monmouth. I am actually dating the president, so within the fraternity is not a problem. I doubt it would be a problem crossing fraternities, which is even more disconnected. I would just flat out check with their president if you're afraid it would be an issue. Just be prepared for an entire chapter to be her "big brother" in the sense that they'll be really protective of her