When I was a boy of 16, I sailed on a big steamer from Southampton to New York in a 4-berth cabin with just one other person, a Dutch horticulturalist. One day, he brought an apple back from lunch and he offered me some later in the day. We had no knife. Shortly, he said, "I have the answer" and he literally broke the apple in two by grabbing it in his hands and pulling it apart from the top, near the stem. The break was so sharp that it looked exactly as though the apple had been sliced with a knife. Point: there is often more than one way of disecting something.

There are two issues being discussed here.

The first is the origin of any number of broadside songs, most but certainly not all of which were actually written to be sold on broadsheets. This is great research area and a very interesting topic for enthusiasts to read about. I find it fascinating. As Malcolm points out, somebody wrote the songs. Because people passed freely between Britain and Ireland, even the presumed geographic origin (e.g. oldest printed source) of a song does not necessarily identify the origin of the author. I agree with what Malcolm has written above.               

The second issue is what becomes of the song once it is written. It is rather like a balloon that gets loose. The song goes on a trip and the person who wrote the song is no longer connected to it in any way other than historically. We know that songs of Irish manufacture have been sung in Britain and vice versa. Workers migrated between countries, and men from England, Ireland, Scotland and Wales all served in the British Army, Navy and merchant marine, and exchanged songs while in the service. The song, even if it was written in another country, once it becomes accepted, becomes part of the cultural identity of a people. Depending on the song we are talking about, Frank Harte had a reason for either changing or not changing the text. They were Frank's decisions and, as someone working WITHIN the Irish song tradition, he had the right to make them. He was part of the living tradition.

All the best,      
Dan