jlmc - regarding your initial question as to what happend to the men who came to Australia - here are acouple of clues taken from the Geelong Advertiser card index and the Geelong Cemetery Trust indexes (this was a few years back so they might even be on-line now)
1876 death of Jessie Barclay nee Stewart - wife of Leslie Barclay, buried plot 844 Geelong Western cemetery
Leslie Barclay died aged 81, 19 June 1908, buried next to his wife in plot 844.
Thomas Birrell, not one of the original migration group, born Cellardyke is buried in row 31.
Also Sophia Birrell nee Barclay wife of David Birrell dieded in 1875 and is in plot 844.
David Birrell lived until 1911 and is also buried in this cemetery but I do not have the plot number.
all plot numbers are in the Presbyterian section.
Angela