Mag wrote:

Um, as a professional singer, I am perfectly capable of both reading music, understanding chord structures and changes, varying the tune, adjusting to key changes and broken strings, improvising, making up harmonies as I learn a song and a variety of other things expected of a professional musician.

I gently suggest that you do not have a singer on your hands, you have someone with a nice voice. I would suggest you get a singer.

I don't see how the second statement necessarily follows from the first, especially as there is nothing I can see in the original post that seems to suggest what you are implying by your final sentence.

The original post seemed to be more concerned with helping someone overcome a problem in their singing and was asking for suggestions on how to deal with it in a sympathetic way.