I have no specific idea, but try Googling "locate living people in australia".
I read the original post as it was only Elizabeth that went to Australia and her parents and siblings remain, at least for a while, in Ireland.
Very recent obituaries might be found online but it's usually a matter of luck finding details. However, we've relatives in Dundalk area and I was able to find lots of information on them using Google to find newspaper articles (it did help that I already knew names and dates but the newspaper articles did fill in details and even showed a lot of photos).
