It might be Glycine microphylla. One of the important thing about that species is that it roots at the nodes. I have had another try at keying it using Vicflora, that separates microphylla from tabacina on the angle of the side veins - 30-60 degrees for tabacina, rarely 70; and 80-90 degrees for microphylla. I suspect you will need to take a specimen in to the herbarium. Microphylla always twines; tabacina rarely.
Glycine microphylla is not listed in the new Census of plants of the Australian Capital Territory (30 August, 2019). If you are near the site when it is flowering, could you take a soecimen in to the herbarium please. I assume you have a collecting permit. Thanks. Betty