You can indeed apply and each application is considered under its own merits by the Home Office.
However, you have to consider 2 things:
- Once your parents show interest in immigrating to the UK, they won't get UK visitor visas in the future. So if your attempt to bring them permanently to the UK fails, you won't be able to see them in the UK as visitors.
- As matter of policy, the Home Office was never sympathetic to extended dependent family members. Dependent from an EEA today, how long before turning into dependent of the UK taxpayer?
More and more venues have been developed to refuse these applications or to limit the eligibility. One the major changes is what happened on Feb 1st, 2017. This is meaningful to your case. It's published here:
https://assets.publishing.service.gov.u ... s-v7.0.pdf
Because of that, the Home Office can turn around and tell them they are not eligible at all.
But even before that Feb 1, 2017 change, it wasn't easy to bring the parents of the non-EEA national on the basis that they received a couple of Western Union payments from the UK.
You are making these payments as your brother is also making similar payments from Australia. The claim of dependency to an EEA national is weak to non-existent here. Stronger elements of dependency and/or being part of the household of the EEA national had to be shown when this route was available.