Hi,
May I ask a direct but rhetorical question, please .... Can you place your family in Cowra around the same time as Matthew may have been there? Were they "in town" or on property out of town?
I am happy to look through various offline records for rural NSW that cover the 1920s. I avoid typing this up into public forums, (I have living rellies who were born just before WWI hostilities broke out, they are very private people) but if you care to send me a PM with some clues I will look further, and try to help.
Cheers, JM (born 'on the Lachlan' many decades ago,

)