So, when Phoebe and George were being interviewed by the C of E clergyman, he asked for information and he recorded it. That information included
What is your full name
Where were you born, and he was looking for the place, not just the colony.
What is your age, and if under 21, who is giving consent to the marriage ... this is usually given by the father, and if he is not available, then by the eldest brother aged over 21, and if that brother is not available, then by the mother.
What is your father's name and occupation
What is your mother's name and occupation
What is your own occupation
Have you ever been married
Those details are then recorded in the local parish records, which are not ever meant to be destroyed, (Church laws cause at least two registers to be established and maintained, to be kept separately from each other in fire proof safe rooms etc ).
It is possible that Phoebe gave her birth name as well as her "known by" name, or perhaps she only gave BEVAN ... but she would have given her age, and her place of birth .... And of course, it is those two pieces of information that you are seeking at this moment. And, I think I know someone who may have had access to the C of E records at Cobar when looking up one of their own forebears, I cannot promise to have the information you need, but I can promise to try to give you a pointer or two to either find it directly or to find where the information is currently held. And when you contact those organisations, it is often handy to be able to provide some clues to help those researchers find the entries ... thus the Electoral Roll information about James S Bevan may help you to help them.
Cheers, JM
