This is a temporary visa. You can usually stay in Australia for 18 months.
You can't stay in Australia longer by extending this visa, as you can't be granted another Skilled - Recognised Graduate visa.
You will need to apply for another visa. Family members who apply for the visa must meet the health and character requirements. You can add your children to the application until a decision on your application is made. You can't add any other member of the family unit to your application during that period.