Hi Robyn

Found 3 births to John Balfour and Edith Sarah in SA

Edith Ellen 1878-08-07
Isabel 1879-09-11
Myra Lucy 1886-10-19

Also 2 births in New Zealand

Henry Basil 1875
Charles James 1876

There is also a marriage in SA for Mary Elizabeth Anderson (father listed as John Balfour Anderson) to Roland Young 1897-03-04.

This link for WA BDM and you will find Isabel's marriage to Eric Rumble in 1915.
http://www.bdm.dotag.wa.gov.au/_apps/pioneersindex/default.a...

It would seem that Edith and Myra never married?? Search for the name Anderson and you will see their burials and also one for a John George Balfour Anderson.
http://www.mcb.wa.gov.au/NameSearch/search.php

Searching the Trove website will also give you a bit more info.

Goodluck

cheers jmc