We have had possums for 15 yrs & still don't know a good way to...

We have had possums for 15 yrs & still don't know a good way to get rid of them. If you trap them, because they are territorial you have to release them max 50mtrs away. If you do manage to get rid of it another will just take it's place. We have access to the roof cavity through a opening above the fridge & for yrs one lived up there. Every time we opened the fridge door it would jump down & we would feed it some fruit. It became so tame that she would let us take the baby from her pouch & it almost became non- nocturnal. Often In summer we would see her napping behind the glass door of our combustion fire. We would leave the door open for her to get out but most times she would climb up the flue. The pipe was 150mm dia. & we put a bolt through it dividing in half & it still got through. They can enter through the tightest gaps. We had a hole in the weather boards & every time we replaced it they would rip a hole in the new one. They would come in through the gap between the top of the garage roller door & wall & one lived inside the roller until it got sick of being tumbled around every time we opened it. We have tried lights in the roof cavity & even installed skylights that let light into the roof space. They just curl up in the darkest corner. We had to replace the corr. Iron roof so we fixed up every gap we could see but we still hear them walking around in there. If we leave a door open at night they just walk in right past our dog which they bully anyhow. So after one climbed up on the cupboard & knocked our ipad down & broke it I would like to move them on. I admit we encouraged them when our kids were little but cos we haven't been paying them much attention lately they have become a bit feral, so if anyone has any answers I too would appreciate it. Now don't get me started on bandicoots, grrrr.