abandonment law

Hi any lawyers ,
Just off the cuff,If a person owning a house did a runner didn't pay any outgoing for 30 -40 years.Is there some sort of squatters rights .
When technically Uncle still owns the dwelling ,mum and dad settle any debts mostly to council for rates in arrears Council was about to for close on it.Way back.Lost touch with my uncle whom was left to him when his mum died.He was a maniac hoarder.So we had tip trucks come in and cleared the mess up.He moved away Thought he had passed away,Then TV uncovered a story about a guy that was living in some cars and someone tried to burn him alive .He escaped went to hospital fixedup back on the streets.The guy is 86 now healthy as. meet up with him the other day ,he had the miss fortune of sleeping in a lawyers door way ,He loves living on the street.Tried to persuade him if I put a granny type flat outside would that do ...He wouldn't have a bar of it .
1 sister wrote him a letter and said you still technically own a house ,it has no debt but has maintainence issues.Which we are sick of doing and asked him to sign it over to the family ,.He wants us to rent it out for him, We said at least do a will up and leave it in our name ,or the state will end up with it or the salvation army or some boozer in the streets ...So my sisters kids are living there rent free just pay rates for 10 years.Trouble is a house that old needs paid maintainence .and I been wanting to turf her family out and make the thing start paying for it self property? we are a family of 6 children.
What would you do ???..........BUGGER.......any guidance would deeply be appreciated thanks mal