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Lastly, Australia was a continent holding well over 600 indigenous nations whose people spread out to all part of the continent and evolved into distinct nation groups for tens of thousands of years, right before european settlement. Estimates of the population count at the time of settlement in 1788 range from 300,0000 to over 1 Million. Indigenous Australians are considered have gone through a population 'bottleneck', having moved through and tracing of their early migration from Africa, over into the Middle East, possibly India and South Asia.

https://en.wikipedia.org/wiki/History_of_Indigenous_Australians

Such would develop a greater number of genetic and ethnic markers for each Indigenous nation well beyond the Melanesian markers. You would have quite a number of different indigenous groups making their way into the entire indigenous makeup as they made their way through africa and asia before settling in Australia. This would suggest that early Indigenous Australians would have a very diverse DNA makeup.

https://www.news-medical.net/news/20231214/Study-uncovers-unique-genetic-diversity-in-Australian-Indigenous-populations.aspx

You're talking many different geographic regions along the way and many Australian Indigenous peoples having a diverse DNA structure to other Australian Indigenous peoples - over an estimated 50-60,000yr time period.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4819516/

But in between, you have a greater spreading out of each group from the north to south. Given that no two indigenous persons from different indigenous nations are exactly alike, knowing who could be directly descended from the Darkinjung on the indigenous side is virtually impossible to trace, either from a descendant or an adjacent indigenous nation who may have dealt with the Darkinjung. How can we know who dealt with the Darkinjung? Not to mention, the Darkinjung are essentially an extinct people. They were either killed off or taken away from their lands.

https://paulbuddehistory.com/bucketty/the-darkinjung/

Locating the remains of a full blooded Darkinjung person with DNA that was specific to their people would involve having to source numerous burial sites on their traditional lands and finding the intact remains of an indigenous person that contains any trace amount of DNA from those remains. That's a big IF of whether they can, mind you, that all depends on how well they are preserved. The lands and sites of the Darkinjung are well known.

https://www.darkinjung.com.au/

I can guarantee the Darkinjung LALC will not agree to any Archeological dig on these sites all in the name of genetic testing of bone remains, regardless of the moral, legal and ethical dilemma of that even being considered. Which excludes that avenue from being explored altogether.

I also doubt the owner of the grave site of where Elizabeth Bailey is interred wouldn't want her grave to be dug up for this reason either. I'm sure many of her descendants wouldn't want it disturbed for this reason too.

In conclusion, there's not enough biosample data taken from the greater Australian Indigenous population to gather conclusive results over finding specific markers that makes one "Aboriginal" or not, therefore the matter on that issue is unresolved and wholly unsubstatiated. Given that the total number of people who claim Aboriginality is around 984,000 at the time of writing this, an estimate of about half that number would be full-blooded. That's still too small a sample size in comparison to the rest of the world to find a unique marker of "Aboriginality", that's not including their diverse genetic makeup to begin with.

The important point here is that this singular DNA test of this one unknown individual should NOT be relied upon as confirmation that Elizabeth was not the child of Mary. This is a gross mis-step in locating the facts in the matter and, frankly, as a scientist I find this quite embarrassing.

The only way for this matter to be cleared up reliably is to locate a birth certificate for Elizabeth Bailey, nee. Smith. Documentation on this should state who the birth mother and father is and give us conclusive results. Keep in mind though, Indigenous Australians who gave birth, especially those who lived on traditional lands, had no access to being issued a birth certificate by the Crown right after settlement. This was common practise for many children of indigenous parentage not being issued one right up until the early part of the 20th century, as they were seen as 'fauna' and not officially recognised as part of the population until after the 1967 referendum.

https://aiatsis.gov.au/explore/1967-referendum