Hello. Sorry to reply so many years after you posted your message ; I only just came across it today. With the help of some other family memebers, I have been working on the Mellamphy (originally Maol Anfaidh) family tree for some time. We have information on 17 branches, although we have not yet found how these are all linked. I don't have much on Sarah Mellamphy (although I suspect she is related to my own branch of the family, which also comes from North Tipperary) but I can tell you her father's name was Patrick Mellamphy. She and her husband John Hall had 10 children, 3 of whom survived: Alice, Richard, and James. The only grandchild's name that I have (not sure about year of birth) is one Sandra Robotham, who I believe is still in Australia.
The family tree was online until recently; I should be putting it up on a new site soon, if you are interested.