When there is a problem like this, I have had great success just using a piano arrangement. There are many different levels of difficulty, so you can pick the one that is best for your harp-playing ability. Since I create most of my arrangements at the harp, a fake-book version is usually all I need. Once the tune is in my head, I never look at the music again, and continue to improvise and re-arrange it freely, even during my concerts. Freedom of expression, ha, ha! (I do play the classics by the actual notes of the composer, in concert from memory, unless I am presenting my version of a classic, of course!)
Happy Holidays,
Balfour