Hi there,
It sounds like your production has already passed, but a great tool for future productions would be RehearScorePLUS, if you're not already using it.
You can give the software to your cast as well so they can rehearse at home with it. It has the piano and vocal lines for the show programmed into it one on top of the other so that the cast can rehearse with the vocal line or without it. This should help with pitch issues.
I hope the production ended up being a success!
Best,
Richard