After posting yesterday's post on this topic I decided to try and further refine the chart to distinguish when several people can from one region in Australia or one city in the UK.
I added an addtional column next to the existing columns of cells and then reduced the width of this new column until it was a small square next to each cell. I could then add colours to show same regions or towns as required.
The above section of the chart highlights family born in the Hawkesbury region of NSW as well as family from Glasgow in Scotland. Lots of time could be spent playing with variations of charts. They do provide a way of showing the range of locations members of a family can come from.