Complex sentence: A few Commonwealth governments have made alternative arrangements to share the burden, e.g. under a reciprocal agreement Canada and Australia are responsible for each other's citizens, and the British embassy is only responsible for Canadian and Australian citizens if neither country is represented.
Split into simpler sentences: A few Commonwealth governments have made alternative arrangements to share the burden, such as the Canada-Australia Consular Services Sharing Agreement. The British embassy is only responsible for Canadian and Australian citizens if neither country is represented.