3 related family members were buried (Church of England, deaths from 1913-1926) at Bell, Queensland cemetery facing westward. They are the only 3 doing so. What may have been the reason/cause for this change to protocol?
Without knowing anything more about your relatives, Wikipedia has the following (unattributed, unverified) details about burial orientation:
Historically, Christian burials were made supine east-west, with the head at the western end of the grave. This mirrors the layout of Christian churches, and for much the same reason; to view the coming of Christ on Judgment day (Eschaton). In many Christian traditions, ordained clergy are traditionally buried in the opposite orientation, and their coffins carried likewise, so that at the General Resurrection they may rise facing, and ready to minister to, their people.
In Islam, the grave should be aligned perpendicular to the Qibla (i.e. Mecca).
Based on that commentary alone, perhaps they were members of clergy?