Can I Use Artwork Created from Coloring Books?

Dear Rich: My daughter, who has Down syndrome, loves to color design coloring books such as Ruth Heller's Designs for Coloring. She has a good eye for color and puts hours into each picture. She would like to submit her work to a book compiled by Woodbine Publishers about Down syndrome artists. Is she allowed to? We think you should try to get permission first. Assuming you can get in touch with the copyright owners, we believe they are likely to grant permission. We think that because the reproduction won't harm their sales, it's the right thing to do, and it's good public relations. If you can't get permission, we think you can probably get away reproducing the imagery without permission (though we can't guarantee that result).
How do you get permission? The copyright is likely held by the Ruth Heller Trust Fund but we think the place to start your request is with Grosset and Dunlap/Penguin Putnam Books for Young Readers, the publisher. They have an online permission system and a set of FAQs explaining the process and their online database indicates they control about a dozen Ruth Heller books. If the coloring book you are using is not covered, perhaps G&P can lead you to the proper source or to the trust.
Can you use it without permission? We think including one or two images (with proper attribution) would probably not trigger a cease and desist letter. Although the copyright pages of the coloring books don't specifically grant permission for uses like yours, a coloring book is an implied invitation to create a derivative work. It can also probably be argued that the sale of a coloring book implies a limited right to post and reproduce the resulting "colored-in" works. And for what it's worth, the company has not objected to the posting of colored-in versions of their imagery at Amazon. Again, we can't guarantee that the copyright owner won't object to your use, but it's difficult to imagine that they would.