FOUR octaves? Holy crap RB, that's some kinda singing superpowers! My Early English singing tutor told me I had an unusually good range, and I fit Jack's two and a half (*just* - with some oiling)

Otherwise - regards Sinead's Lagan Love, don't be put off by a particular singers breathing techniches or phrasing. If your friend's a singer, she will see straight through those surface elements and hear the *arrangement* and think about it in terms of how she might approach it it herself. That's what I think anyhoo.

As an aside. For my part I hate 'Enayisation' of anything - but Sinead - while not technically brilliant a far as I can tell, has a deeply emotional voice. She's like a naturally gorgeous girl, who slaps on heaps too much makeup because she thinks the boys will fancy her that way.