What does it mean that Australian immigrant brothers and sisters can apply for Australian reunion in other ways?

You should be talking about family reunion and immigration. It means that when half or more of your family members immigrate to Australia, you can apply for family reunion immigration, bring your relatives together and immigrate together. For example, if there are three or five members in your family, including mom and dad, brother and sister, or younger brother and sister, and there are five members in your family, when you are the only one who successfully immigrated to Australia, then your family members are not allowed to apply for relative immigration, but any of your family members can successfully immigrate to Australia except yourself, then your whole family can go. If you are an only child, parents can also apply for family reunion immigration after immigrating to Australia. Do you want the whole family to go there? Bless you! !