It appears that Barbara Thomson was born in December 1837 in Scotland, after the Thomson family she is currently attached to, arrived in Australia December 1837.
She married in Scotland and emigrated to Queensland 1865. She is not named in Death Certificates for 'parents' Alexander or Mary.
Jean Thomson, also currently in this family as a sister of Barbara, was born in Scotland 1830 and died in Scotland 1909. Other children in this family born after her were brought out from Scotland to Australia.
One of the Matches on Jean's profile states that her parents are in Scotland in 1861.
So could Barbara and Jean belong to another Thomson family with the same or similar parents' names.