Parents In Law

Im am an Australian citizen living in the UK and am soon to be married,

I am pretty sure that my partner will be elligable on my citizenship, but will her parents?

Both will be over 45 at the time of emigration and they have 3 children,

1 will be with me in Oz
The other will be staying in UK maybe,
the other lives in Holland
(only mentioned this coz something was mentioned about dependants)

Can any help or offer advice?

Thanks

Her parents most likely won't be eligible as dependents (don't they have some income of their own?).

A contributory parent visa won't be an option until the "balance of family" test is met, and with 3 children, that means at least 2 living in Australia.

start at http://www.immi.gov.au