::The Geographical Names Board is the official government agency responsible for registration of place names in NSW so it's authoritative. If something is registered as a suburb then it legally and verifiably is a suburb. In NSW, a township isn't defined, it's somewhere between a town and a village, which are defined as: 
 ::* town - "A commercial nucleus offering a wide range of services and a large number of shops, often several of the same type. Depending on size, the residential area can be relatively compact or (in addition) dispersed in clusters on the periphery" 
 ::* village - "A cohesive populated place in a rural landscape, which may provide a limited range of services to the local area. Residential subdivisions are in urban lot sizes." 
 ::Nowhere does it verifiably say that a township can't fit inside a suburb and this is reasonable because the size of a suburb is not defined anywhere. You're assuming that a suburb is a small place and that's not true. There are plenty of large suburbs. Kooragang, a suburb of Newcastle, covers 35.4 km2, which is larger than Anna Bay at 23.1 km2. As I've already pointed out, with sources, the town of Anna Bay fits well within the suburb of Anna Bay, and if a town can fit in a suburb then a township can. and a town can easily fit in the suburb of Kooragang. Please note that the Geographical Names Board isn't the only authority to be involved with registering place names. Local councils register the place with the GNB and the GNB has to register the place in accordance with the law. Claiming that they got it wrong based on your opinion is classic original research.