Just an update since I last wrote - we've been slowly trawling through the information online and have now ordered a couple of marriage certificates relating to Jonathan (the Durrant that came to Australia on the Coromandel).
My own belief (which I hope to be confirmed or otherwise by the certificates) is that Caroline was Jonathan's 2nd wife, and that Jonathan is the same Jonathan you mention as listed in the 1851 census with wife Sarah, and children Henry, John (Jonathan) & Sarah. (He was listed as a bricklayer, as was Jonathan on the ship to Australia listing). It seems likely that something happened - perhaps death - in 1851 to wife Sarah & the eldest child, and that Jonathan remarried quite quickly (we are looking at a possible marriage to a Caroline Archer in 1852). I have found two death records listed that might be contenders, but have also found a Henry Durrant aged 19 at 1861 census living as the son of a woman who is not named Durrant, so perhaps Henry was taken in by extended family? That's purely speculation but, whatever - he did not come to Australia, just Jonathan & Caroline, and the 2 other children.
What's so interesting is that all our Australian relatives have presumed that they've resulted from the Jonathan/Caroline line. I strongly believe that this is not so - that the young Jonathan on the boat, along with his sister Sarah Elizabeth, was a product of Jonathan & Sarah.
Once we've ascertained Jonathan's (2?) marriage details, I can then move on to his parentage, and perhaps we'll turn up something about your Joseph.
