I am just so fascinated with it all and i'm having a great time.

Welcome to the "addiction" of Family Research,
Caitlin!
You seem to be on the right track with the two marriages in your last posting. Have you been able to work out the two 1871 marriages for Margaret CARNS and Mary SWEETING with the same references?
As I indicated earlier, if you haven't done so already, you should obtain that certificate for confirmation. The same probably goes for getting a number of other certificates to prove things one way or the other.
I'm not too sure how much researching you have done, but with Certificates - Birth and Marriage Cert's are usually more reliable due to the informant being a named person on that certificate, whereas with Death Cert's, the informant
could be anybody, and the information supplied could be just guess or heresay i.e.not factual.
Lastly, with certificates, you don't necessarily have to buy original copies from the Registry. You can buy typed transcripts from authorised transcription agents for about half the cost of an original. There are three agents for NSW BDM transcriptions.
Les