|Female digger by Van Gogh|
Your book. Just so we're clear ... you plan to offer a book with new "digger lyrics" for existing songs. For example, you would state, "Sing these lyrics to Twinkle Twinkle Little Star" and then include your new lyrics but not the musical notation or original lyrics, right? You are definitely okay to do so with any songs published in the U.S. before 1923 or any that otherwise fall into the public domain for other reasons. We think you'll be okay with non-public domain songs, too, but we can't guarantee safe passage. That's because lyrics are separately copyrightable and if you're borrowing too much from the originals, you would create an infringing derivative. That said, we kind of doubt that the copyright owners are going to care enough to do something about this project so we're inclined to think you can proceed as planned.
Do intellectual property lawyers exist in every city? Probably, check one of the many Canadian legal directories (type "canada legal directory" into your search engine).