Hi Robert
Just a couple of things - the AVRI is basically a copy of the BDM records - so it only has the same parents (given names only) as per the NSW BDM. It does give the church for baptisms/marriages/burials when this is missing from the NSW records - not sure why they miss it sometimes and include it sometimes. The parish for the 1842 birth is
Sydney ( Parish Not Stated), Roman CatholicIf you are going to start guessing some death records, I suggest you read up on the transcription agents. They will provide a lesser fee to check records for certain details. You can list the records in sequence for them to check. Thus said, there are quite a few in this case, and given the dates, the information you need to verify a death (e.g. name of wife) may be missing. Even if you purchase a full transcription, it is still cheaper than the registry certificates.
http://www.bdm.nsw.gov.au/familyHistory/howToSearch.htm#TranscriptionAgentUntil the early 1900s the information on NSW certificates is variable - although the detail you mention (parents, children) is supposed to be on the certificates it is not alway there. If parent names are on the index record, they will be on the certificate/transcript (although there is still a possibility that the mother's maiden name may be missing). If parent names are not on the index, they will not be on the certificate/transcript. According to the comment here, forms were not used until 1918 for the collection of the information - which may be why some data is missing.
http://www.bdm.nsw.gov.au/celebrate/civil.htmlDeath certificate information is also very dependant on the knowledge of the informant
I've checked a couple of early certificates I have
1879 - gives parents, marriage details & time in NSW - gives number of children of each sex, but not names. My only earlier death records for NSW are burials (pre 1855) which give name age & preacher. Little else
1905 - death certificate contains all details including names & ages of all living children
Re interstate marriage - I did check NSW TAS VIC and WA which are the 4 states on the AVRI and didn't find anything that looked suitable
Trish