Can you tell us where you get the name Margaret BYRNES from?
Ah BUN and Winifred CALLAGHAN had a daughter named Catherine in 1882 in Queensland, and it was Catherine who married Robert STORY in 1927, also in Queensland. Catherine died in 1938. Her funeral notice names her as "Winifred Catherine STORY".
Queensland BDMs are free to search online, and you would need to purchase the birth cert of one of Winifred's children to find where Winifred and Ah Bun were born.