If you are talking Births, Deaths, and Marriages Graham then no Member Trees on Ancestry (some millions of them) have an internal reference number which refers back to the owner.
If you are taking about the collections, or databases, they too have reference numbers but they aren't accessible by the users.
Are the BDM numbers you are given references to the NSW indexes perhaps?
You can send me a private message with more data if you like. I've done a fair amount of research in Oz and my convict ancestors were all sent to Van Diemen's Land. Still, I can find my way around NSW.
