The Outback

HI new to all this ....I’m not sure where to start as my circumstances are complicated and I cannot find the right documentation be able to make an appointment to speak with someone....I moved to Australia in 1967 with my parents when I was three years old under the assisted passage migration scheme and granted residency and I have documentation for this. I spent the next twelve years living in Australia where I went to school and grew up, I have documentation for this. My family moved back to the UK in October 1979, only to return back to Australia in 1999. Under which visa I do not know. I remained in the UK as I am now a serving police officer of 25 years. Both my parents and sister all became Australian Citizens and I have their Australian Citizen documentation. My brother was born in Australia and currently resides there. I have strong family ties with my brother and his children, aunts, uncles, cousins, nieces and nephews, god children. Both my parents and my sister are now deceased and ashes scattered in Australia. I have been back to Australia 23 times since 1979 and I have documentation to show this. I do not know what visa was granted to my family in 1967 when we arrived as I was on my parent’s passport and whether it had permanent residential status for me to return as I was only fifteen. Im now divorced and need to go back to OZ to my remaining family. Has anyone had the same situation ?