Hello again,
Sorry to bail on this post for a day, but I was working a crazy shift at work. Thank you all for your thoughts and suggestions.
She does indeed have a private instructor along with her daily band class and practice sessions with me. Her instructor was the one who suggested she my be ready to move up to a larger mouthpiece as she is consistently hitting G's with the 3C. She inherited my full lip structure (think Liv Tyler), and like me plays with the edges of the rim in the pink part of the upper lip. I have read this can cause problems but haven't experienced any personally that I am aware of but I don't want her to be handicapped by it as we are all unique. My big concern is some sort of muscle strain or other negative physical affects and problems to watch out for.
As for the smaller mouthpiece theory, I had a professor in college encourage me to to try that to the extent of rolling my lips inward against my teeth. Trust me, it was not a pleasant experience. I do know there are trumpet players out there with large lips buzzing small mouthpieces but I have not been successful with it. Larger seems to be what I need unless I am doing something incorrectly.
Thanks again for all the help, you guys are wonderful!
Joseph