Returning resident information

Hi Im looking for advice from anyone in a similar position to me. I moved to Australia under assisted migration scheme (£10.00 pom) in 1967 with my family. In 1979 we all moved back to UK with a new addition (brother), as I was only 15 I couldnt stay in OZ...believe me I wanted to. My sister returned in 1980 became a OZ citizen. My Mum and Dad returned in 1997 and became OZ citizens. My brother returned in 2010 and lives in QLD and was born in Australia. I am due to retire in next couple of years having done 30 years in police service. My Mum, Dad and Sister are all deceased now and ashes in OZ. I am going through a divorce and have two teenage children. They will be 20 and 21 when I retire and not sure of there plans yet.
I want to come back to OZ to be with my brother and all my family who also moved out in 1968, home is where the heart is. I have been back to OZ 23 times over past 30 years. I cannot find any information as to what visa was on my parents passports when we first returned in 1979, were they issued an ATR or RE wet stamp in there passports as I was on there passports back in the day.
I dont fit criteria for RRV however there is a category for RRV with strong family ties.
Any information would be appreciated. As you can see my situation is complicated.