Thanks to everyone who responded to my request.
Before posting my wish for an easy way to edit the existing lyrics sources, I had probably read most of the threads discussing the subject of lyrics and the LyricsReloaded plugin. Thus, I went in expecting that the solution may prove to be not as plain as I had hoped it to be. I am still hoping, though. Good lyrics sources are more or less finite, and once those are loaded, this more comprehensive list should not require too much attention.