Your Immigration Expert
Your Children May Not Be Australian
As your ex-husband is only a resident in Australia there are several reasons to doubt your children are eligible for Australian Citizenship and may only apply for residency under strict conditions which would not automatically afford you entry to Australia.
I would need to know a great deal more but I doubt you would qualify to enter leaving your oldest child without a route into Australia either. We have provided a guide on working visas and how to qualify, this requires your to have skills in demand in Australia.
Overall, I am not confident about your case and would suggest you do a great deal more research on the subject before submitting any applications.
If my reply may seem harsh, it is because of my experience which tells me this case is a mess and it is better to stop the dream before it turns into a nightmare of expensive fees with little or no return.