The only Ealden on the Port Jackson Anthology is James who arrived in 1831 on the Lady Harewood (2), after being tried in Maidstone in 1830, sentenced to Life, aged 41yrs. Other lists give the trial date more exactly as 15th July 1830.
He is on the register for the retribution hulk, at Woolwich.
James Ealden is on the 1841 census at Parramatta,
He was granted a conditional pardon, which was gazetted (in NSW) September 1848
There is no record of James Ealden using and alias.
I can find no NSW BDM records for James Ealden using a variety of alternate spellings, but there is a death record for Elijah Eildon in Parramatta in 1892. There is the solitary marriage record for Elijah Ealden and Rosanna Lynch in C of E Melbourne in 1840.
Ealdon is an easy name to mis-spell, but I wasn't successful with any thing I tried.
You have obviously been very thorough in your research, and I'm sorry I have little to add.
Hi Rosie and thank you. I have never found/seen the Elijah Eildon death record, so thats a new one on me... but it's in 1892 - there are so many fishy things about this - either as you say all the records are with different spelling or something else was up. If Elijah Eildon is the same Elijah who married Rosanna, then he was still alive (and presumably still married to Rosanna/Rosina, when she married James Hammond... all very interesting. Her name change is also interesting, as its not a pronunciation type of error, and she appears to be literate, and signing her own name on the certificates. She came out here as Rosanna, married the first time as Rosanna, and then married the second time as Rosina, had a daughter called Rosina and died as Rosina. I'll keep plugging away, if anyone else has anything to add - even a theory, I'd be glad to hear it.