Você precisará se inscrever separadamente, mas seus aplicativos podem ser processados ​​juntos.

O governo australiano Página de visto de visitante afirma:

Include family

You can't include family members in your application. A separate application must be made for each member of your family, including those listed on your passport.

If other family members are applying for this visa, your applications can be processed together. Learn more when you apply for the visa.