I was quite surprised to find so many of the McMorrough clan looking for information on our history. I would love to read the transcriptions you are making of your mother's tapes, as I have just started my search and have little to go on.
My father (John Francis McMorrow) was born in New York in 1921. His mother, who he seldom spoke of (due to old grudges), was unmarried when he was born, so his grandfather (I believe his name was Francis McMorrough) became his legal guardian, and gave him the McMorrow name. Apparently the folks at Ellis Island didn't care for the way my great-grandfather spelled his name on his immigration form, which is how it was changed to McMorrow. I understand this was a pretty common occurence for immigrants arriving in New York.
Sadly, my dad passed away some years ago, and talked little about his side of our family. So any history of the McMorrough clan is welcome.