I'm no legal expert or anything, but the work belongs to her if commissioned (as compared to poets or fiction writers). Unless specified in writing, she can do with it as she pleases.

Someone correct me if I've erred in my simple explanation.

Speaking of payment, you phrase it exactly that way-- speaking of payment. I'd recommend getting something firmly established in writing, as in a letter of agreement detailing payment arrangements, etc. The letter could take off, and she could hypothetically deny ever agreeing to anything. If it's someone who doesn't want to cough up, just arrange a royalty-based payment (perhaps with a deposit up-front, but I know how tough it is to get going).

Alex Stiner