Actually – any government can cripple Australia-if a Parliamentarian makes a visit to any country that country could in effect legislate that a visitor or someone with any connection grandfather etc or even if an ancestor fought in on their soil can be deemed a citizen of that country . Then they can really wipe out Parliamentary representation in Australia.
So what is required is Commonwealth legislation defining what Australia recognises as valid citizenship of another State.
It is not sufficient for another State to unwittingly co-opt anyone with a tenuous relationship – like an aunt or mother applying for an adult child. Or Australia recognising children born to Islamists overseas as Australian citizens.
Also anyone granted citizenship should be able to be stripped of their citizenship if they are convicted of a crime that carries a sentence of more than 1 year [ even though they may not receive that from the judiciary – for that portion judges should not be involved]]