Thank you Heather for your reply. In Australia, personal privacy is heavily protected by law, but the kind of records I am looking for could potentially be manually compiled by collecting data from living family members - which is one of the things I would like to do. Obviously, though, I would need a list of currently living family members.
Your suggestion of going to a family cemetery also is a good one, and I have identified severalnpeople as previously unknown family by doing this.
Unfortunately, the huge difficulty is that most of my pre-1870 ancestors come from the other side of the world, mostly Ireland, some in England, and it is not practical to go over for a quick look, this being over 24 hours away by airplane (we live in Australia).
Your advice is useful, though, as there are some family who migrated directly to the USA from Ireland, and a small number who left Australia to live in the Usa.
Thank you,
Mark Hanlon