Thanks so much to all who have helped here. I have a lot to look at.
Catherine Ah Bun's child Sidney Roy Hopwood is my grandfather. I have been able to trace the Hopwood (Lucas) line back to England as one came out on the first fleet and married a woman who came on the 2nd fleet. I have mainly been stuck on this Ah Bun person.....and the same problem on my mothers side. Her grandfather was adopted and no birth certificate.