To get adequate service for a statutory demand, postal delivery isn't sufficient.

For this, you need a process server to deliver the documents to a company director.

If you can't find them, it becomes very difficult to serve them.

It is possible to obtain a judgement in absentia/claiming you have had service, forcing the part(y/ies) to come forward to dispute this (and they will win) but that will present an opportunity to serve again as documents can then be served on their lawyers/them personally.

Caveats on any properties held in sole (or joint) titles is usually a prudent measure ...