Watch the Danny Boy: Adding Harmony Voices online guitar lesson by John Knowles, C.G.P. from Fingerstyle Journals
Now in the next section, I keep my focus on the melody and put the harmony parts in the background... like a singer and an orchestra. And because there are more notes, I'm going to be careful with my left hand fingering and practice to make each move as effortless as possible. Then, I repeat that section with a few small variations.