The only way I can think of is look here-http://www.awm.gov.au/research/people/all/?Name=reynolds&...
This gives you the list of all the Reynolds who served in WW1- look at the embarkation rolls. You can also eliminate those who died from the Roll of Honour.
Then you would have to go to here- http://www.naa.gov.au/collection/using/search/
Click on Begin you Search, go to Name search at the top and put in surname Reynolds and pick WW1 from drop down line.
Then you would have to go through each service record and see if there is any mention of what you have said after the war.
Not easy and time consuming, but I can see no other way, sorry.
I suppose you could go through the Nominal roll on AWM also and see which ones came home later and look at those first.